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Re: [APBR_analysis] Re: Cross Generational Simulating/Comparisons

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  • bchaikin@aol.com
    I would say that the philosophy does have pertinence. Neither philosophy nor stats can live in an isolated world. Too often, statistical results are
    Message 1 of 29 , Jan 27, 2003
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      I would say that the philosophy does have pertinence. Neither philosophy nor stats can live in an isolated world. Too often, statistical results are interpreted blind of the rest of the world, which is why oat bran is good for you one week and deadly the next.
      It comes down to where the burden of proof lies. I think there is a significant burden for stats to carry because they already have the word "lies" associated with them. If stats don't see what others see very clearly, they not only have to say why they don't see them, they have to show that they've tried every means to see them, and then
      they have to really show why people are deceived by their eyes.

      well then i guess the question in this instance is what are the stats - all the stats available - telling us? if someone persists in stating that lower scoring per game, for instance, means lower (or higher, or better) offensive productivity, and that this is how he defines offensive productivity, and at the same time this individual also states that "...i expect that defenses were also improving...", how can you have both without showing the process as a whole is "improving"?......if we can show thru other statistical methods that offensive productivity has not improved with time, such as with league averages for pts/poss, and they choose not to believe it, then why a stats analysis discussion group?...

      without taking into consideration other statistical evidence provided, then again we are looking at some one saying the sun does not set in the west and refusing to look to the west to see it. in other words, then just what is he saying? arguement for the sake of arguement?....

      Yup, compared to the 1970s, we see more switching on defense, better team defense. Better team offense too...better defensive rotations too.

      again someone states a similar arguement, better offense and better defense, but neither arguement backs up their statements with any sort of statistical evidence. if i was to state that 20 or 30 or 40 years ago both offense and defense were actually better than today (which i am not) everyone would say to prove it, but these quotes simply assume they are correct and do not feel the need to show any kind of statistical evidence....

      Right now, Bob is implying that the burden is not on the stats to show that cross-generational sims are reliable, but I would say that it is. How a simulation should handle different rules hasn't been answered.

      again, have rule changes affected the game in a way measurable statistically? has defensive 3 sec, the convoluted zone rules of the lates 80s early 90s, the recent zone defenses, changed say FG% differently than before, altered pts/poss differently than before? these parameters have fluctuated over time (at least from 77-78 to today) but i can see no discernable connection between their fluctuation/changing and any specific rules changes - the process as i see it appears the same. can you show a correlation to a rule change affecting the game in a measurable way? other than when they brought in the 3pt line, which in itself increased 3pt FGA (decreased 2pt FGA) and increased 3pt FG%, the league overall FG% and say pts/poss did not appear to be affected by the rule change..

      How a simulation should handle different average heights and weights hasn't been answered.

      every season NBA teams of varying heights and weights play each other, and that doesn't seem to cause any problems. is there some sort of discernable pattern to equate an advantage or disadvantage statistically in the span of one season such that NBA teams of varying hts and wts cannot be compared directly? if so state it, if not then why should this be an impediment to more than one season of comparisons?...

      How a simulation should handle the very different league averages in pace or points per possession hasn't been answered.

      no? then how can a simulation handle them within even the same season? again the 90-91 season is a prime example. the evidence is there, you can state that the question "...hasn't been answered..." but in fact, over the span of a single season, it has. what is the impediment in playing the 115 poss/g 90-91 nuggets versus the 93 poss/g 90-91 pistons? the bottom line is that this actually occurred in the same season, and can be modeled - its in the same season, the game paces are very different, so different in fact that its comparable to the game pace of a much longer time span than just a single season....

      Setting up frameworks for these philosophical questions is relevant for trusting any simulation.

      fine, are you saying the frameworks can be set up then? or no? and why?...

      we now have 6'10" players who can dribble and pass the ball, and better rotation of the ball by even the weak teams...

      "....6'10" players who can dribble and pass the ball...." this is evidence? as if in the late 1950s and 1960s 6'10" players who could score big time couldn't pass and/or dribble? shaquille o'neal gets probably 90% of his points from within the paint, but he sure can dribble and is a helluva passer too - as were players in their prime like walt bellamy (6'10"), bob petit (6'9"), elvin hayes (6'9"), dolph schayes (6'8"), and maurice stokes (6'7") and many others. this idea that players back then were lumbering giants scoring only because they were big and close to the basket is ridiculous.....schayes never stopped moving, hayes was as quick as a cat when he was young, bellamy averaged just under 30 pts/g his 1st 3 seasons in the league facing chamberlain and russell quite often each year (only 9 teams in the league) -although i'll admit watching him in the early/mid 1970s he really appeared to be dragging his caboose around the court...

      better rotation of the ball? basketball of the late 1950s and 1960s was a faster paced game than today, and from watching tapes it appears more overall passing and more player movement without the ball, not as much standing around as this past decade.....not a better game, just a different style, one that required just as talented an athlete as does today's game....and athletes that could withstand the rigors of an 80-82 games season just as today...

      This doesn't preclude cross-generation simulation, but figuring out what the game pace would be between say the 1977 Nuggets and 2003 Nuggets, and how that pace would affect each team's offensive and defensive efficiency, is a tough analytical problem.

      again, why is this a tough analytical problem? we can sim in-season teams of varying game paces, why not consecutive seasons, seasons 2-3 years apart, seasons 5-10 years apart, seasona 20-30 years apart? what says that you can't do this? and do it accurately?

      bob chaikin
      bchaikin@...





    • John Hollinger <alleyoop2@yahoo.com>
      Bob s challenge to prove this got me thinking more about how basketball has changed in the last 30 years, such that players from 30-50 years ago wouldn t be as
      Message 2 of 29 , Jan 27, 2003
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        Bob's challenge to prove this got me thinking more about how
        basketball has changed in the last 30 years, such that players from
        30-50 years ago wouldn't be as successful if they played today -- my
        premise being that a guy like Dave DeBusschere or Bailey Howell would
        be less effective today than he was then, even after adjusting for
        weights, diet, jets, etc.

        The more I think about it, the answer is that the talent pool has
        massively expanded.

        There have been three expansions of the pool in NBA history, two well-
        known and one not. The first was the breaking of the color bar in the
        1950s, which let guys Russell and Chamberlain and the Big O into the
        league. The third was the advent of the international player in the
        1980s and 1990s, an expansion that is still continuing.

        But the one that had the biggest impact and is least talked about is
        the second one -- the desegratation of the South.

        Try to find a significant African-American player from the South
        before 1960. Your list will consist of Sam Jones. All the other guys -
        - Wilt, Russell, Big O, etc. -- from the north or west.

        By 1970, just six more guys had joined Sam Jones: Wes Unseld, Willis
        Reed, Walt Bellamy, Walt Frazier, Elvin Hayes and Lou Hudson.

        So there were seven impact African-American players from the South in
        the NBA in 1970, and zero international players.

        ************


        Fast forward to today. The entire Eastern Conference All-Star team
        consists of African-Americans from the South. Two of the West's
        starters are international, and one other is from the South
        (Garnett). That's 8 of the 10 starters in the All-Star game. And if
        you thought Shaq should start ahead of Yao it's still 8 out of 10.

        None of these guys would have been playing 30-40 years ago, because
        their route was blocked. The major universities, most notably
        Kentucky, were fielding all-white teams until around 1970, and
        using 'one black starter' or similar quotas well afterward. As a
        result, the change that started with the arrival of Unseld and
        Frazier in the late 60s took 20 years to ripple its way through the
        entire league.


        To see how it changed it, make a list of the most dominant players of
        the last decade or two and then choose sides:

        The international/southern blacks team has:

        -- Hakeem Olajuwon. Shaquille O'Neal. Michael Jordan. Charles
        Barkley. Scottie Pippen. Clyde Drexler. Alex English. Joe Dumars.
        Dale Ellis. Derek Harper. Mo Cheeks. Jeff Malone. Sidney Moncrief.
        Robert Parish. Dennis Rodman. Dominique Wilkins. James Worthy. Ray
        Allen. Tim Duncan. Dirk Nowitzki. Kevin Garnett. Penny Hardaway.
        Allen Iverson. Shawn Kemp. Karl Malone. Toni Kukoc. Antonio McDyess.
        Tracy McGrady. Alonzo Mourning. Dikembe Mutombo. Jermaine O'Neal.
        Mitch Richmond. Ben Wallace. Arvydas Sabonis.

        The white north american/northern blacks team has:

        -- Larry Bird. Isiah Thomas. Adrian Dantley. David Robinson. Patrick
        Ewing. Kevin Johnson. Magic Johnson. Kobe Bryant. Chris Mullin. Tim
        Hardaway. Grant Hill. Jason Kidd. Gary Payton. Stephon Marbury.
        Reggie Miller. Steve Nash. Paul Pierce. Glen Rice. David Robinson.
        John Stockton. Antoine Walker. Rasheed Wallace. Chris Webber. Kevin
        Willis.

        It's no contest, right?

        The massive influx of quality players who previously had no access to
        the path to the professional game -- either because nobody in their
        country played or because of Jim Crow -- is the reason I think there
        is a major difference in the quality of play between 30 years ago and
        now. More than half the good players in the league simply wouldn't be
        there if it was 1970.
      • bchaikin@aol.com
        Okay, let s take things point by point and be done with it? if you tire of the exchange of ideas concerning this discussion, once you have already made your
        Message 3 of 29 , Jan 27, 2003
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          Okay, let's take things point by point and be done with it?

          if you tire of the exchange of ideas concerning this discussion, once you have already made your position clear, but do not wish to be bothered to be asked to defend your postion with stats in a stats analysis group, then maybe this wasn't the forum for you to "...add a few pennies worth of thought on the issue of inter-temporal comparsions of NBA performance..."...

          Me:

          the superiority of the average team in the early 80 to its 60s counterpart was on the order of 10 to 12 points per game (at a modern game pace).  This is equivalent to how much better the best Bulls team was to the league average.

          Bob:

          not sure what these numbers mean or where they are coming from....how did you arrive at this or derive these numbers?...

          so let me get this straight, you are saying you have statistically come up with a way to show that if the average NBA team of the early 1980s (about 109 pts/g) played an average team from the 1960s (115 pts/g) or early 1960s (almost 116 pts/g), the avg 80s team would beat the average 60s team, on average, by 10-12 points, normalizing for modern times. the 95-96 bulls outscored their opponents that year by just over 12 pts/g. so you are saying the difference in ability to win of an average early 1980s NBA team versus/compared to an average 1960s or early 1960s is the same as the 95-96 bulls to the suns or hornets of 95-96 (.500 teams that year)...

          is this correct?...

          Me again:  The calculation I referred to was made by computing a measure of offensive (or equivalently defensive) productivity that I called "points per common possession" versus "common possessions per game".  In the former case, the computation is average points scored in the numerator and average common
          possessions in the denominator.  Common possessions are, by definition and construction, the same for both teams in a particular game (hence attractive for purposes of comparison and analysis) and are basically calculated by subtracting the number of offensive rebounds from the conventionally defined number of possessions a team enjoys in a game.

          fine...so fill in the blanks below so we can compare...or show us your numbers that show how you arrived at your result...

                                   pts/      sec/      pts/
          year        FG%      g      poss     poss
          5960      .410     115.3
          6061      .415     118.1
          6162      .426     118.8
          6263      .441     115.3
          6364      .433     111.0
          6465      .426     110.6
          6566      .433     115.5
          6667      .441     117.4
          6768      .446     116.6
          6869      .441     112.3
          6970      .460     116.7
          7071      .449     112.4
          7172      .455     110.2
          7273      .456     107.6
          7374      .459     105.7
          7475      .457     102.3
          7576      .458     104.3
          7677      .465     106.5

                                   pts/
                                   48min
          7778      .469     107.7    13.4      1.000
          7879      .485     109.8    13.5      1.029
          7980      .481     108.5    13.8      1.041   
          8081      .486     107.5    14.0      1.043
          8182      .491     107.9    14.1      1.058
          8283      .485     107.9    13.8      1.037
          8384      .492     109.2    14.0      1.063
          8485      .491     110.2    13.9      1.066
          8586      .487     109.5    13.9      1.059
          8687      .480     109.2    14.1      1.067
          8788      .480     107.6    14.3      1.065
          8889      .477     108.5    14.1      1.062
          8990      .476     106.3    14.4      1.065
          9091      .474     105.5    14.5      1.063
          9192      .472     104.5    14.7      1.067
          9293      .473     104.5    14.7      1.066
          9394      .466     101.0    15.0      1.049
          9495      .466     100.6    15.3      1.069
          9596      .462      98.8     15.5      1.063
          9697      .455      96.2     15.8      1.053
          9798      .450      94.8     15.7      1.036
          9899      .437      90.9     16.0      1.009
          9900      .449      96.9     15.3      1.030
          0001      .443      94.0     15.6      1.020
          0102      .445      94.8     15.7      1.034

          DeanO has pointed out that "...this trend looks about right, even if my calculations have slight differences...". so if we are defining offensive productivity as pts/poss, i see similar pts/poss numbers with varying FG% and pts/g and game pace for 77-78 thru today. if your number show a different trend for prior to 77-78, lets see them...

          For missing data series internal to the sums (that is for turnovers and offensive rebounds in the time periods in question) as I noted before, I extrapolated values

          fine - you made some assumptins/estimates for missing parameters...

          and conducted a bit of sensitivity analysis to see if reasonable deviations from
          assumed values would overturn results. 

          overturn what results, your 10-12 pts spread?...

          They could not. (As noted, the offensive rebounding percentage was remarkably stable over succeeding time period.)

          Finally, the "12 points per game" was, if I recall correctly, taking he observed increase in productivity and prorating it at the modern end-point game pace. (Which is to say it would have been higher using the earlier endpoint where there were more
          possessions per game, but no more meaningful.)

          so lets see how you came up with this using the your numbers....

          Then to repeat, "what the numbers mean" is that teams were having fewer possessions (defined to encompass all they would do with the ball before it would revert to the opposing team) per game yet they were scoring more points. 

          lets see some numbers to back this up...

          These are the off-setting trends that allow no other explanation (yet offered) than the offenses were - on net - getting better, much better.

          this is how you defend your position, by stating that the results allow "...no other explanation..."?

          Me:

          Just looking at the average offensive productivity over the time in question, what one sees is that it improved dramatically (the 12 points per game above).

          Bob:

          would love to "look" at it but you're not showing anything...

          Me again: As noted, I did not have these data on file or in hand, as they were done long ago.  Perhaps I will spend the time to recalculate them.  In the meantime, if you have these data at your fingertips, feel free to make the calculation. 

          feel free to explain it...

          There is no ambiguity as to what they say.  The trends are almost strictly monotonic as I recall.  Pick any starting year in the mid to early 60s (or late 50s for that matter) and any end point in the late 70s to early 80s.  The numbers speak clearly.

          show me the beef.....

          Me:

          Now, those who believe we stand on the shoulders of giants might be inclined to say that defenses got worse as opposed to offenses having mproved.  Is this view tenable?  The answer is "no" because the trend is accompanied by a dramatic slowing of the game. 

          the answer is not "no", the numbers from 77-78 thru today show that the slowing of the game does not correlate well with pts/poss, on the contrary from 77-78 thru today the values fluctuate from 1.000 to the early 90s there is an increase to almost 1.070. 77-78 and 98-99 show very close pts/poss numbers of 1.000 and 1.009 yet the game pace is significantly different. based on that why should anyone believe your pre-77-78 numbers without seeing them?....

          This slowing, all else equal, implies that offensive productivity should have decreased. .  Why?  It either means fast-break baskets were being reduced or that the half-court offenses were having to work harder for shots.  But offenses improved, dramatically...

          sorry, don't see it....

          Bob:

          here are some number for you to chew on:

                                  pts/      sec/      pts/
          year        FG%   48min   poss     poss
          7778      .469     107.7    13.4      1.000
          7879      .485  109.8    13.5      1.029
          7980      .481     108.5    13.8      1.041 
          8081      .486     107.5    14.0      1.043
          8182      .491  107.9    14.1      1.058
          8283      .485     107.9    13.8      1.037
          8384      .492     109.2    14.0      1.063
          8485      .491     110.2    13.9      1.066
          8586      .487     109.5    13.9      1.059
          8687      .480     109.2    14.1      1.067
          8788      .480     107.6    14.3      1.065
          8889      .477     108.5    14.1      1.062
          8990      .476     106.3    14.4      1.065
          9091      .474     105.5    14.5      1.063
          9192      .472     104.5    14.7      1.067
          9293      .473     104.5    14.7      1.066
          9394      .466     101.0    15.0      1.049
          9495      .466     100.6    15.3      1.069
          9596      .462      98.8     15.5      1.063
          9697      .455      96.2     15.8      1.053
          9798      .450      94.8     15.7    1.036
          9899      .437      90.9     16.0      1.009
          9900      .449      96.9     15.3      1.030
          0001      .443      94.0     15.6    1.020
          0102      .445      94.8     15.7      1.034

          sec/poss is the avg time per team possession, pts/poss is the avg points scored per team possession. you can see a general trend in a slower game thru time secs/poss) but no such similar trend in offensive productivity...

          as you can see total points scored and game pace have next to nothing to do with offensive productivity per team possession. 1978-79 and 1999-00 have the same pts scored per team possession (1.029 and 1.030) yet vastly different game paces, vastly different FG%s, etc. if you should doubt these pts/poss numbers, DeanO or any other of the stats gurus in this discussion group can verify (or for that fact deny) them....

          since i can't accurately calculate pts/poss prior to 77-78, i can't present similar evidence. but the above clearly shows that over a 24 year time span of the NBA that offensive production per team possession is not directly correlated to game pace (slowing down the game or speeding it up)......

          Me again: I have chewed on your numbers,and I am happty to tell you what flavor impressions they leave.  First, I should say that the food is not what I ordered.  You pick as a starting point of your series, the end point of the trend I asserted. 

          the stats are available from 77-78 on, you haven't presented your numbers nor estimates for data missing prior to that. are we to simply take your word on it?...

          No matter.  Let's talk about what you present.  First of all, I am not sure how you
          calculate possessions, but never mind. 

          i don't know how you or DeanO do either, but apparently his and my numbers are similar...

          As I recall my rendering of the data in the timespan you present (and again, these are somewhat distant recollections) once you factor out the increasing weight of the three-point shot in augmenting average offensive productivity (as I noted previously, in passing, it took a remarkably long time for teams to figure out how to optimize the three point shot in the context of team offenses) what the 80s represents is a period of essential "stagnation" (neither offenses or defenses gaining at the expense of the other) followed by a decline beginning in the very late 80s or early 90s. 

          this i do not see...i see similar pts/poss for early 1980s to mid 1990s...and similar numbers for late 70s and late 90s early 2000s.....if you have different numbers for offensive productivity lets see them to back up your statements...

          Now, nothing you present overturns this impression of mine. 

          surprising...

          And as to these changes in the 90s, taking the data you present above (let's say '91-'92 to '01-'02) what they say is that there was a 6.8% increase in seconds per possession and a 3.1% decrease in points per ossession. 

          from 89-90 to 96-97 i see simlar pts/poss numbers but a game consistently slowing down...no correlation there.....i see a lowering of pts/poss in the next 5 years but it fluctuates, no discernable pattern...

          At 91.72 possessions per game in '01-02 this means teams were scoring 3 points per game less than the decade prior. 

          in 01-02 the 1.034 pts/poss is similar to the 82-83 pts/poss of 1.037, yet they scored
          more points per game in 82-83 (108 pts/g vs 95 pts/g) simply becuase the game pace was faster...

          If this represents a net improvement in average defense over the decade, Is there anyone who doesn't think that that is significant? 

          looks to me like a fluctuation of pts/poss over a 24 season period, despite a general slowing of game pace...

          in 78-79 i see .485 FG%, 110 pts/g, and 13.5 sec/poss with 1.029 pts/poss. in 99-00 i see .449 FG%, 97 pts/g, 15.3 sec/poss, but the same pts/poss of 1.030....are we not looking at the same data?...

          Again, for context, the average NBA champion is only about 6 to 7 points (again pace dependent, blah, blah, blah) than the average team in the league.  So 3 points is close to half the way from mediocrity to championship status.

          not sure what you point is again...

          Me:

          And the only explanation I can deduce is that offenses were disciplining themselves (through improved coaching I surmise) and expunging bad shot selection.  Now, as
          > I also said before, I expect that defenses were also improving during this time so that the 12 point estimate is in fact a low estimate of the actual improvement in these two decades.

          Bob:

          have no idea where this is coming from...

          Me again: About what have you no idea? Is it the deduction that the offsetting trends of game pace and offensive productivity in the 60s and 70s

          show us some data...

          necessarily mean (again, absent an alternative explanation) that there is a net offensive improvement in the average NBA team over time?  If so, I don't know how to explain it any more clearly.  Perhaps someone else can help.

          perhaps...

          Or is it the point that the "12 point" estimate is a low-ball?  This simply means that all the offsetting trends can identify is the net offensive improvement.  Now one can believe then that the relentless assault of offenses on defenses were met with no
          countermoves on the latter's part.  In this case, the estimate is not low, but this of course seems rather hard to believe, hence the low-ball claim.

          Me:

          And to continue.  If one accepts the general and continuous improvement of the game over the two decades mentioned, then it becomes arbitrary to imagine that progress stopped then.  The reasonable prior belief is that the slow decrease in offensive productivity after this point is the result of defensive improvements, rather than some technological
          retrogression.

          you've made a number of generalizations...show us when - what years - the trend increased, with yearly numbers, when it stopped, when it decreased, etc....may be obvious to you, but you are not being definitive. the above 77-78 to 01-02 numbers show otherwise...

          unless of course you are not defining offensive productivity with pts/poss but something else...

          Bob:

          what slow decrease in offensive productivity? i see similar offensive productivity in 77-78 to 80-81 as i see in 97-98 to 01-02, with the higher productivity per poss of the 1980s being higher and fairly constant...

          technological retrogression?? like what, bring back the jump ball after every score??...

          e again: Again, I refer you to the fact that the endpoints you chose for your analysis were not the period I was speaking of. 

          actual data for ast, st, bs doesn't exist for prior to 73-74 (except ABA) and TO prior to 77-78. you say you've made estimates for seasons prior to this but don't show them, and present your findings as dogma...

          But additionally, to repeat somewhat, your selection is rather precious, as there is a lot going on over the 15 year period you show.  Productivity goes up and down again.

          24 year period - while there is a general increase in time per poss, or decrease in game pace - no definitive pattern for pts/poss or offensive productivity versus game pace for this 24 year period is evident...and you want us to believe - that without you showing the data - that there is a trend for seasons prior to this...

          And as for the term "technological retrogression", I am sorry that it confused you.  I was simply pointing out (regarding the 90s decrease in offensive productivity)

          you mean 97-98 to 01-02 don't you?...

          that the alternative to believing that defenses had on net improved relative to offenses, one must believe that somehow offenses got worse, somehow forgetting to do as well in a given year what they could do a few years past (that is to say that their "technology" - the means by which they produce points - had retrogressed - as opposed to progressed).  Clear?

          if you say so...

          Me:

          And finally, I made what I think is a very persuasive argument for the superiority of the trained athlete in more recent times.  In the form of a question, if there are not some return to his efforts, why is he killing himself in the gym?

          Bob:

          a nice philosophical arguement but not pertinent for stats analysis..

          in 73-74 nate archibald was making $400,000 a year. the average salary (not mean but average) at the time was - i'm guessing - 1/8 to 1/4 of that, somewhere in between $50,000 to $100,000. the average american income for a working adult at that time was probably about $5,000 - $15,000 a year. for that kind of scratch are you saying athletes didn't keep themselves in shape, in condition, to play pro hoops? that that kind of dough wasn't enough incentive to also kill themselves in the gym in the early 1970s like athletes kill themselves today? i don't know the average salaries in the early 1960s, but i know chamberlain and russell were arounf $100,000, and i'll bet the league avg salary was well above the average working adult salary at the time - and this doesn't take into account the salary war started by the ABA in the late 60s early 70s.....i'm also guessing the average player trying to make the NBA in the early 60s (let alone today), if he didn't make it, went on to become a doctor or lawyer with a high salary...

          just becuase the athlete of the 1960s didn't have access to the weight training they had today and all the equipment doesn't mean they didn't do whatever they could to be inshape to play at the pro level...

          Me again:  Are you kidding me?  Statistics are a useful and indispensible tool for divining truth, but they are not the sole means; no matter if they are your fetish of this paragraph in this argument.  As for numbers, the point was made, and made
          unanswered, that in every athletic endeavor where competition is additionally against a fixed measure (say 100 yds run, or pounds lifted, or spins in air completed) there has been a relentless yet decreasing improvement over time. 

          so absolute records are broken against static measures. basketball is a relative measure, player versus player, like baseball or any of the other team sports. the arguement is pointless. are the players better athletes - better bodies, better nutrition - yes im sure, but better basketball players? if no one breaks wayne gretzky's records in the next 100 years, does that mean hockey had peaked in athletic performnace in the early to mid 1980s??

          You seem to plead specially for basketball's exception when it is observed that its athletes are bigger and stronger.  And as for the question I pose regarding why a rational athlete would devote excruciating hours in a gym to no benefit, it is also pertinent for the analysis. 

          the assumption that pro basketball athletes train harder and longer now than 10, 20 or 30 years ago is ridiculous. players back in the 60s and 70s and late 50s ran just as much in practice, played 35+ or 40+ min/g just like they do today, at an even faster paced game...they all saw the benefit of good training, to make an excellent living. every generation has its hotplate williams and oliver millers, as they have their dolph schayes and john havliceks and john stocktons and karl malones...

          Me:

          There is the "proof".  I look forward to any alternate explanation of these facts and inferences.

          Bob:

          see above...

          Me again: See above indeed.

          Me:

          All this aside, I should say that I have nothing but the highest regard for the notion of using simulations for analyzing the game of basketball.  To my mind, they are the best method for understanding the effect of marginal changes in game variables.

          However, they are not useful - only highly deceptive - in determining the competitiveness of NBA teams from different eras.

          no more deceptive than someone stating teams from one era are 10-12 points better than another era without showing the numbers...

          Bob:

          words from the wise i guess....

          Me again:  see above...

          i'd love to believe your statements, but you don't show how you arrive at the numbers...


          bob chaikin
          bchaikin@...

        • Dean Oliver <deano@rawbw.com>
          Lots to respond to, but one quick thing for now. ... weights hasn t ... other, and ... discernable ... span of ... compared ... impediment to ... So, if I can
          Message 4 of 29 , Jan 27, 2003
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            Lots to respond to, but one quick thing for now.

            --- In APBR_analysis@yahoogroups.com, bchaikin@a... wrote:
            > How a simulation should handle different average heights and
            weights hasn't
            > been answered.
            >
            > every season NBA teams of varying heights and weights play each
            other, and
            > that doesn't seem to cause any problems. is there some sort of
            discernable
            > pattern to equate an advantage or disadvantage statistically in the
            span of
            > one season such that NBA teams of varying hts and wts cannot be
            compared
            > directly? if so state it, if not then why should this be an
            impediment to
            > more than one season of comparisons?...
            >

            So, if I can show that on average shorter teams do worse than taller
            teams and I can show that 1960's teams are on average shorter than
            1990's teams, is that reasonable evidence that the 1990's teams are
            likely to be better? Is that a fair test?

            DeanO
          • bchaikin@aol.com
            How a simulation should handle different average heights and weights hasn t been answered. every season NBA teams of varying heights and weights play each
            Message 5 of 29 , Jan 27, 2003
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              How a simulation should handle different average heights and weights hasn't been answered.

              every season NBA teams of varying heights and weights play each other, and that doesn't seem to cause any problems. is there some sort of discernable pattern to equate an advantage or disadvantage statistically in the span of one season such that NBA teams of varying hts and wts cannot be compared directly? if so state it, if not then why should this be an impediment to more than one season of comparisons?...

              So, if I can show that on average shorter teams do worse than taller teams and I can show that 1960's teams are on average shorter than 1990's teams, is that reasonable evidence that the 1990's teams are likely to be better?  Is that a fair test?

              DeanO

              did you or did you not pose the statement "...how a simulation should handle the different average hts and wts hasn't been answered..."?

              if so, and your next comments are the way you believe to best resolve your own question, then go for it...

              i on the other hand do not see any problems whatsoever. every season has tall teams, every season has shorter teams. i can name champonship teams with tall players playing most of the minutes, and ones with players shorter than most of the teams playing the majority of the minutes..

              i seem to remember a team winning six titles in the past decade with only one 7 footer, and he played just one season of more than 2000 min in those title years. they had one 6'10" player who for 3 straight titles was 3rd on the team in minutes, behind two players that were 6'6" and 6'7" in height. for their 3 later titles they had one 6'8" guy, and one 6'9" guy coming in off the bench. their 7'2" guy never played as many as 2000 minutes in one of those championship seasons. neither the 6'10" guy in the 1st 3 titles nor the 6''8" guy in the 2nd 3 titles was excessively heavy...

              bob chaikin
              bchaikin@...







            • Dean Oliver <deano@rawbw.com>
              ... should handle ... resolve your ... The point was that you seem to claim that height differences don t matter. Compare one season to the next and your
              Message 6 of 29 , Jan 27, 2003
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                --- In APBR_analysis@yahoogroups.com, bchaikin@a... wrote:
                > did you or did you not pose the statement "...how a simulation
                should handle
                > the different average hts and wts hasn't been answered..."?
                >
                > if so, and your next comments are the way you believe to best
                resolve your
                > own question, then go for it...
                >

                The point was that you seem to claim that height differences don't
                matter. Compare one season to the next and your simulator does about
                right even though average heights change.

                Coaches and scouts certainly use height as a tool for evaluation.
                Height helps shoot over people, pass over people, and catch balls.
                There is a logical basis for height meaning something.

                And there is a statistical basis, too. An inch over the league
                average height improves both an offense and a defense.
                Statistically, it's true, at least. Not every tall team wins and not
                every short team loses. But we're talking statistics, right?

                I can give you the numbers, but if you don't think it's true, what's
                the point?


                >
                > i seem to remember a team winning six titles in the past decade
                with only one
                > 7 footer, and he played just one season of more than 2000 min in
                those title
                > years. they had one 6'10" player who for 3 straight titles was 3rd
                on the
                > team in minutes, behind two players that were 6'6" and 6'7" in
                height. for
                > their 3 later titles they had one 6'8" guy, and one 6'9" guy coming
                in off
                > the bench. their 7'2" guy never played as many as 2000 minutes in
                one of
                > those championship seasons. neither the 6'10" guy in the 1st 3
                titles nor the
                > 6''8" guy in the 2nd 3 titles was excessively heavy...

                By the way, those Bulls that you are subtly referring to were not
                short. They exceeded the average league height in those years by
                playing tall guys at every position but center. Overall, they were
                one of the tallest teams each and every one of those 3 years (5th,
                8th, and 5th).

                DeanO
              • bchaikin@aol.com
                The point was that you seem to claim that height differences don t matter. Compare one season to the next and your simulator does about right even though
                Message 7 of 29 , Jan 28, 2003
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                  The point was that you seem to claim that height differences don't matter.  Compare one season to the next and your simulator does about right even though average heights change. 

                  no - i am not claiming anything. it is you claiming/pointing out that the sim does not take into account height differences from year to year, and that it should. my point is the sim does just fine reproducing real life results within a single season where there are players ranging in height anywhere from 5'3" to 7'7" - based on their and their teams real life statistics. statistics in a season are the results of what happened when players of different heights played each other, no? players play multiple seasons, span over not just years but decades...

                  if one was to truly believe your arguments for why you could not play one season versus another, whether they be close to each other in time or from different eras, simply because the teams don't in real life play each other, then there would never have been a world series in baseball between AL and NL teams when the leagues only played games within their leagues. since the AL only played their AL counterparts, and the NL teams only played their NL counterparts, how could anyone have possibly believed or trusted the result of a match between the AL and NL champions in a world series?? i mean - after all - they never played against one another...this is your logic...

                  same for ABA teams versus NBA teams. they never played one another during the seasons - how could anyone trust the results between an ABA team and an NBA team, when they have never played each other before? based on your logic they couldn't.....

                  but i seem to remember alot of world series and ABA/NBA exhibitions...

                  Coaches and scouts certainly use height as a tool for evaluation.  Height helps shoot over people, pass over people, and catch balls.  There is a logical basis for height meaning something.

                  height is merely one of a number of facets to a player's game that coaches look at. are you saying height is the only tool coaches/scouts use for evaluation? the major, dominant tool? for every coach you can quote me that says height is a dominant factor, i can quote you one that says speed is more important - for shooting over/thru people, for passing around people, for catching balls. there is a logical basis for speed meaning something also...

                  And there is a statistical basis, too.  An inch over the league average height improves both an offense and a defense.  Statistically, it's true, at least.  Not every tall team wins and not every short team loses.  But we're talking statistics, right? 

                  fine, take every team, multiply the players heights (on each of the teams) by their minutes played to get the avg height on the court for each team, and run that thru history by charting it against W-L record, and come up with some kind of correlation factor...

                  but don't forget to also do this for speed, and dribling ability, and passing ability, and other facets of players......otherwise, based on your logic, you would be leaving out important facets that a sim also does, no?...

                  I can give you the numbers, but if you don't think it's true, what's the point?

                  so what if it is true? what is your point? are you suggesting that teams from certain eras need to get a 1 or 2 or some odd point spot in each game played between teams of different eras to account for some statistical height bias? or that rebounding or some other stat should be adjusted because one era is an average of one inch lower than another? what about within the same season?...

                  what about a statistical bias for speed? are you going to ignore speed but somehow compensate teams for height differences? how can you make some adjustment for height but not speed?...

                  i could probably do a study that would show that there is a statistical bias between NBA blue eyed players and brown eyed players, as if that really is applicable to the playing of the game, and if there was indeed a statistical bias, such that say brown eyed players scored more (and scoring determines who wins or loses) that some statistical bias should be awarded to teams with more brown eyed players...

                  when you decide to develop a simulation, if you believe you should award or take away from a team's totals merely because of height differences, or speed differences, or brown/blue eyed differences, be my guest..

                  if you are going to look at and/or compensate statistically for player height, then you probably should also for player weight, whether a player is R or L handed, whether they are fast or slow, because i'm sure all of these separate facets can be shown to have a statistical bias. how can you pick and choose which to use and which not to use?....

                  but since players of different heights, different speeds, and different eye color all produce the statistics, i'll just use the actual statistics...

                  bob chaikin
                  bchaikin@...









                • Dean Oliver <deano@rawbw.com>
                  One last try. If a team of 6 7 guys wins in a league where the average is 6 5 , would that team do as well in a league where the average is 6 7 ? My sense is
                  Message 8 of 29 , Jan 28, 2003
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                    One last try.

                    If a team of 6'7" guys wins in a league where the average is 6'5",
                    would that team do as well in a league where the average is 6'7"? My
                    sense is No. Coaches/scouts say No. The stats say No. Bob says
                    Yes, it's already accounted for in their basic stats.

                    Other questions for me to deal with.

                    --- In APBR_analysis@yahoogroups.com, bchaikin@a... wrote:
                    > The point was that you seem to claim that height differences don't
                    matter.
                    > Compare one season to the next and your simulator does about right
                    even
                    > though average heights change.
                    >
                    > no - i am not claiming anything. it is you claiming/pointing out
                    that the sim
                    > does not take into account height differences from year to year,
                    and that it
                    > should. my point is the sim does just fine reproducing real life
                    results
                    > within a single season where there are players ranging in height
                    anywhere
                    > from 5'3" to 7'7" - based on their and their teams real life
                    statistics.
                    > statistics in a season are the results of what happened when
                    players of
                    > different heights played each other, no? players play multiple
                    seasons, span
                    > over not just years but decades...
                    >
                    > if one was to truly believe your arguments for why you could not
                    play one
                    > season versus another, whether they be close to each other in time
                    or from
                    > different eras, simply because the teams don't in real life play
                    each other,
                    > then there would never have been a world series in baseball between
                    AL and NL
                    > teams when the leagues only played games within their leagues.
                    since the AL
                    > only played their AL counterparts, and the NL teams only played
                    their NL
                    > counterparts, how could anyone have possibly believed or trusted
                    the result
                    > of a match between the AL and NL champions in a world series?? i
                    mean - after
                    > all - they never played against one another...this is your logic...
                    >
                    > same for ABA teams versus NBA teams. they never played one another
                    during the
                    > seasons - how could anyone trust the results between an ABA team
                    and an NBA
                    > team, when they have never played each other before? based on your
                    logic they
                    > couldn't.....
                    >
                    > but i seem to remember alot of world series and ABA/NBA
                    exhibitions...
                    >
                    > Coaches and scouts certainly use height as a tool for evaluation.
                    Height
                    > helps shoot over people, pass over people, and catch balls. There
                    is a
                    > logical basis for height meaning something.
                    >
                    > height is merely one of a number of facets to a player's game that
                    coaches
                    > look at. are you saying height is the only tool coaches/scouts use
                    for
                    > evaluation? the major, dominant tool? for every coach you can quote
                    me that
                    > says height is a dominant factor, i can quote you one that says
                    speed is more
                    > important - for shooting over/thru people, for passing around
                    people, for
                    > catching balls. there is a logical basis for speed meaning
                    something also...
                    >
                    > And there is a statistical basis, too. An inch over the league
                    average
                    > height improves both an offense and a defense. Statistically, it's
                    true, at
                    > least. Not every tall team wins and not every short team loses.
                    But we're
                    > talking statistics, right?
                    >
                    > fine, take every team, multiply the players heights (on each of the
                    teams) by
                    > their minutes played to get the avg height on the court for each
                    team, and
                    > run that thru history by charting it against W-L record, and come
                    up with
                    > some kind of correlation factor...
                    >
                    > but don't forget to also do this for speed, and dribling ability,
                    and passing
                    > ability, and other facets of players......otherwise, based on your
                    logic, you
                    > would be leaving out important facets that a sim also does, no?...
                    >
                    > I can give you the numbers, but if you don't think it's true,
                    what's the
                    > point?
                    >
                    > so what if it is true? what is your point? are you suggesting that
                    teams from
                    > certain eras need to get a 1 or 2 or some odd point spot in each
                    game played
                    > between teams of different eras to account for some statistical
                    height bias?
                    > or that rebounding or some other stat should be adjusted because
                    one era is
                    > an average of one inch lower than another? what about within the
                    same
                    > season?...
                    >
                    > what about a statistical bias for speed? are you going to ignore
                    speed but
                    > somehow compensate teams for height differences? how can you make
                    some
                    > adjustment for height but not speed?...
                    >
                    > i could probably do a study that would show that there is a
                    statistical bias
                    > between NBA blue eyed players and brown eyed players, as if that
                    really is
                    > applicable to the playing of the game, and if there was indeed a
                    statistical
                    > bias, such that say brown eyed players scored more (and scoring
                    determines
                    > who wins or loses) that some statistical bias should be awarded to
                    teams with
                    > more brown eyed players...
                    >
                    > when you decide to develop a simulation, if you believe you should
                    award or
                    > take away from a team's totals merely because of height
                    differences, or speed
                    > differences, or brown/blue eyed differences, be my guest..
                    >
                    > if you are going to look at and/or compensate statistically for
                    player
                    > height, then you probably should also for player weight, whether a
                    player is
                    > R or L handed, whether they are fast or slow, because i'm sure all
                    of these
                    > separate facets can be shown to have a statistical bias. how can
                    you pick and
                    > choose which to use and which not to use?....
                    >
                    > but since players of different heights, different speeds, and
                    different eye
                    > color all produce the statistics, i'll just use the actual
                    statistics...
                    >
                    > bob chaikin
                    > bchaikin@b...
                  • bchaikin@aol.com
                    One last try. If a team of 6 7 guys wins in a league where the average is 6 5 , would that team do as well in a league where the average is 6 7 ? My sense is
                    Message 9 of 29 , Jan 28, 2003
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                      One last try.

                      If a team of 6'7" guys wins in a league where the average is 6'5", would that team do as well in a league where the average is 6'7"?  My sense is No.  Coaches/scouts say No.  The stats say No.  Bob says Yes, it's already accounted for in their basic stats.

                      if you are going to pose questions, but then answer your own questions for me yourself, need i be in the discussion?....

                      i never said yes to this question, so please do not attempt to verify your position by posing questions but then also answering them for me...

                      we were not talking about a league of 6'7" guys nor 6'5" guys nor any other league other than the NBA (except maybe the ABA), a league where the variation in height changes little from season to season. if you want to do a study of average team height on a year-by-year basis and plot it versus W-L record over time, and present it here as statistical evidence to verify your points for determining some sort of correlation or adjusment factor, go for it. more statistical eveidence is always good. but i'll still look at the NBA stats the players generate and not worry about their height, weight, eye color, or political affiliations...

                      if a league of 6'7" 150 lb guys with very short arms wins in a league of 6'5" 250 lb guys with very long arms, would that team do as well in a league where everyone else was 6'7" 250 lbs with very long arms? my sense is who cares about any multiple number of factors that can all present their own different statistical bias's? just look at the stats they produce....

                      bob chaikin
                      bchaikin@...







                    • schtevie2003 <schtevie@hotmail.com>
                      ... Bob: if you tired of the exchange of ideas concerning this discussion, once you have already made your position clear, but do not wish to be bothered to be
                      Message 10 of 29 , Jan 29, 2003
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                        --- In APBR_analysis@yahoogroups.com, bchaikin@a... wrote:

                        Bob:

                        if you tired of the exchange of ideas concerning this discussion,
                        once you have already made your position clear, but do not wish
                        to be bothered to be asked to defend your postion with stats in a
                        stats analysis group, then maybe this wasn't the forum for you to
                        "...add a few pennies worth of thought on the issue of
                        inter-temporal comparsions of NBA performance..."...

                        Me Now:

                        Actually, I don't tire of an exchange of ideas. Not in the least. All
                        that I find tiresome is being obliged to repeat myself because
                        you do not find it in your interest to respond to vexing arguments.
                        And the only idea that has been imparted to me by your
                        responses so far is that you have a vested interest in a "sim",
                        and you want to use it in completely inappropriate ways, and it
                        doesn't really matter what anyone says. Fair enough, I suppose;
                        it's your toy, play with it as you will.

                        This is not to say that none of your comments could be
                        construed to have been offered in good faith. Specifically your
                        request for data is perfectly reasonable. And I am happy to
                        provide it. See below. But first repeating the punchline...

                        *****************


                        Me Before:

                        the superiority of the average team in the early 80 to its 60s
                        counterpart was on the order of 10 to 12 points per game (at a
                        modern game pace). This is equivalent to how much better the
                        best Bulls team was to the league average.

                        Bob:

                        not sure what these numbers mean or where they are coming
                        from....how did you arrive at this or derive these numbers?...

                        ...so let me get this straight, you are saying you have statistically
                        come up with a way to show that if the average NBA team of the
                        early 1980s (about 109 pts/g) played an average team from the
                        1960s (115 pts/g) or early 1960s (almost 116 pts/g), the avg 80s
                        team would beat the average 60s team, on average, by 10-12
                        points, normalizing for modern times. the 95-96 bulls outscored
                        their opponents that year by just over 12 pts/g. so you are saying
                        the difference in ability to win of an average early 1980s NBA
                        team versus/compared to an average 1960s or early 1960s is
                        the same as the 95-96 bulls to the suns or hornets of 95-96
                        (.500 teams that year)...

                        is this correct?...

                        Me Now:

                        That is absolutely correct. More precise numbers below.

                        ********************


                        Me Before:

                        The calculation I referred to was made by computing a measure
                        of offensive (or equivalently defensive) productivity that I called
                        "points per common possession" versus "common
                        possessions per game". In the former case, the computation is
                        average points scored in the numerator and average common
                        possessions in the denominator. Common possessions are,
                        by definition and construction, the same for both teams in a
                        particular game (hence attractive for purposes of comparison
                        and analysis) and are basically calculated by subtracting the
                        number of offensive rebounds from the conventionally defined
                        number of possessions a team enjoys in a game.

                        Bob:

                        fine...so fill in the blanks below so we can compare...or show us
                        your numbers that show how you arrived at your result...

                        pts/ sec/ pts/
                        year FG% g poss poss
                        5960 .410 115.3
                        6061 .415 118.1
                        6162 .426 118.8
                        6263 .441 115.3
                        6364 .433 111.0
                        6465 .426 110.6
                        6566 .433 115.5
                        6667 .441 117.4
                        6768 .446 116.6
                        6869 .441 112.3
                        6970 .460 116.7
                        7071 .449 112.4
                        7172 .455 110.2
                        7273 .456 107.6
                        7374 .459 105.7
                        7475 .457 102.3
                        7576 .458 104.3
                        7677 .465 106.5

                        pts/
                        48min
                        7778 .469 107.7 13.4 1.000
                        7879 .485 109.8 13.5 1.029
                        7980 .481 108.5 13.8 1.041
                        8081 .486 107.5 14.0 1.043
                        8182 .491 107.9 14.1 1.058
                        8283 .485 107.9 13.8 1.037
                        8384 .492 109.2 14.0 1.063
                        8485 .491 110.2 13.9 1.066
                        8586 .487 109.5 13.9 1.059
                        8687 .480 109.2 14.1 1.067
                        8788 .480 107.6 14.3 1.065
                        8889 .477 108.5 14.1 1.062
                        8990 .476 106.3 14.4 1.065
                        9091 .474 105.5 14.5 1.063
                        9192 .472 104.5 14.7 1.067
                        9293 .473 104.5 14.7 1.066
                        9394 .466 101.0 15.0 1.049
                        9495 .466 100.6 15.3 1.069
                        9596 .462 98.8 15.5 1.063
                        9697 .455 96.2 15.8 1.053
                        9798 .450 94.8 15.7 1.036
                        9899 .437 90.9 16.0 1.009
                        9900 .449 96.9 15.3 1.030
                        0001 .443 94.0 15.6 1.020
                        0102 .445 94.8 15.7 1.034

                        DeanO has pointed out that "...this trend looks about right, even if
                        my calculations have slight differences...". so if we are defining
                        offensive productivity as pts/poss, i see similar pts/poss
                        numbers with varying FG% and pts/g and game pace for 77-78
                        thru today. if your number show a different trend for prior to
                        77-78, lets see them...

                        Me Now:

                        Well, here are my numbers. They summarize the yearly average
                        team performance in the league. There are four columns. The
                        year refers to the end year of the season. "CP/game" is
                        "Common Possessions per Game". "P/CP" is "Points per
                        Common Possession". "P*/CP is the same stat except the
                        points are modified to subtract out the third point of completed
                        three pointers. Finally, "3pt effect" differences the two previous
                        columns.

                        Year CP/game P/CP P*/CP 3pt effect
                        57 116.4 .856 .856
                        58 124.7 .855 .855
                        59 124.5 .870 .870
                        60 131.2 .879 .879
                        61 132.9 .889 .889
                        62 131.4 .904 .904
                        63 124.5 .926 .926
                        64 121.5 .913 .913
                        65 122.4 .904 .904
                        66 126.1 .916 .916
                        67 126.6 .927 .927
                        68 124.8 .934 .934
                        69 121.7 .923 .923
                        70 122.0 .957 .957
                        71 119.7 .939 .939
                        72 116.4 .946 .946
                        73 114.7 .938 .938
                        74 111.7 .946 .946
                        75 108.5 .946 .946
                        76 109.6 .952 .952
                        77 110.5 .964 .964
                        78 111.0 .977 .977
                        79 109.7 1.005 1.005
                        80 107.3 1.019 1.012 .007
                        81 105.9 1.021 1.016 .005
                        82 104.7 1.037 1.031 .006
                        83 107.0 1.015 1.010 .005
                        84 105.7 1.042 1.036 .006
                        85 106.1 1.045 1.036 .008
                        86 106.2 1.038 1.029 .009
                        87 105.0 1.047 1.034 .014
                        88 103.5 1.045 1.030 .015
                        89 104.9 1.041 1.021 .020
                        90 102.4 1.045 1.024 .021
                        91 102.0 1.043 1.020 .022
                        92 100.7 1.046 1.021 .025
                        93 100.7 1.045 1.015 .030
                        94 98.7 1.028 .995 .033
                        95 96.8 1.048 .991 .057*
                        96 95.5 1.042 .980 .062*
                        97 93.9 1.032 .967 .064*
                        98 94.2 1.015 .968 .047
                        99 92.7 .987 .939 .048
                        00 96.7 1.008 .957 .050
                        01 95.1 .997 .946 .051
                        02 94.4 1.011 .956 .055

                        Now before discussing trends and repeating the arguments, let
                        me lay out the sources and methods behind these statistics.

                        All data for the "NBA average" are from the Official NBA Guide.
                        "CP/game" is the following sum of terms (divided by games
                        played): Field Goal Attempts + 0.45 * Free Throw Attempts + 1.05
                        * Turnovers - 1.045 * Offensive Rebounds. What this statistic
                        represents again are the number of common possessions
                        between a team and its opponent, or alternatively expressed, the
                        number of continuous possessions - continuous meaning no
                        additional possession is counted on an offensive rebound. Why
                        the various factors. Possessions are disposed of as (1) field
                        goal attempts, (2) two shot free throw attempts (three shot free
                        throws are ignored) which I estimate as one half of 90% of all
                        attempts (the other 10% being technicals and attempts after
                        made shots) hence 0.45, (3) turnovers, where a 5% estimate of
                        team turnovers is added, and (4) offensive rebounds, where
                        4.5% is the estimate of team offensive rebounds. It should be
                        noted that none of the results are sensitive to the factors chosen
                        which is obvious as the last two terms effectively cancel
                        eachother out.

                        For the missing turnover and offensive rebound series prior to
                        1974, I extrapolated using 1974 data. Specifically, for offensive
                        rebounds, I calculated an offensive rebounding percentage for
                        missed field goal attempts of 28.7 (and assumed a constant 5%
                        value for offensive rebounds of missed final free throws). This
                        should not be a controversial value as the percentage hovers
                        quite closely about 30%. And for the turnover series, I assumed
                        a stable relationship of turnovers to field goal attempts and two
                        point field goal attempts, and this value in 1974 was 0.198. In
                        this case, given the downward trend over time in turnover rate,
                        this value is almost certainly biased low which would have the
                        effect on the data of biasing CP/game down and P/CP up - that is
                        to say exaccerbating the trends I identify.

                        On to the analysis...

                        What are the apparent trends. Well, I don't think there is any
                        ambiguity on the point that the CP/game series trends
                        downward over time. Given that I started off recalling data over
                        the 60s and 70s, let me take '60 and '79 as endpoints to begin
                        the discussion. Note a drop in game pace from 131.2 to 109.7
                        possessions per game, a decrease of 15.6%. And during which
                        time offensive productivity increased 11% (.879 to 1.005). Put
                        another way, the average team in 1979, playing at its slower
                        pace would be expected to beat the average team of 1960 by
                        13.82 points per game (.126 P/CP * 109.7 CP/game).

                        And how can this be said to be true? To repeat the argument
                        that hasn't been adressed: slowing the pace of the game, all
                        else equal, is only compatible theoretically with decreased
                        offensive productivity. That there was an increase in offensive
                        productivity must then mean that there was improvement in the
                        way the game was played offensively. This didn't mean that the
                        '79 players were supermen (though they may have been better
                        athletes). It means that the offensive "technology" improved.
                        And what were its intermediate effects: lower turnover rates
                        (identified after '73) and higher field goal percentages (apparent
                        throughout). It also doesn't rule the possibility that defenses
                        improved also, just that on net there was a huge gain for the
                        offenses.

                        Now, Bob, if you can find another explanation for these offsetting
                        trends, and frankly you must if you expect any serious
                        consideration of results from "unadjusted" cross-generational
                        simulations, please provide it. There may be one; I just haven't
                        been able to come up with it over the years. Please try.

                        As for the longer-term trends, picking up from the late seventies,
                        the trends should be clear. The pace of the game continues to
                        fall, and offensive productivity rises and plateaus for a few years
                        in the middle 80s, then begins a "mild" decline (that if you hold
                        the view that losing about four points per game is mild - roughly
                        equivalent to home court advantage or, alternatively, half the way
                        from mediocrity to championship status, as I noted before) or
                        alternatively a very significant decline depending on your
                        perspective.

                        To understand this "dilemna" see the last two columns. They
                        explain the contribution of the three point shot to maintaining
                        "nominal" productivity. For example, in '02 three point shots
                        raised the P/CP by 0.055 (or rougly 5 points per game). How
                        P*/CP should be interpreted then is as a kind of low estimate of
                        productivity. Clearly if teams would only be getting two points for
                        a shot behind the three point line, they wouldn't take as many
                        and would instead opt more for more mid-range jumpers.
                        However, the low estimate might not be that far off. Consider
                        that in '95 through '97 the three point distance was moved in to
                        not much effect.

                        Whatever the case, the essential is this. From the mid to late
                        80's on, offensive productivity has trended downwards along with
                        the pace of the game. In this environment, one could infer that
                        either offenses were getting worse or that defenses were getting
                        better. And my view is already on record. The argument again: if
                        you have a quarter century of relentless net offensive progress
                        (and almost certainly some counterveiling defensive progress
                        as well) it seems absurd to argue that come the mid-80's
                        progress came to a screeching halt and was followed by 15 to
                        20 years of, yes, technological retrogression.

                        So there is the evidence....gotta run...enjoy your dinner.
                      • bchaikin@aol.com
                        Bob: if you tired of the exchange of ideas concerning this discussion, once you have already made your position clear, but do not wish to be bothered to be
                        Message 11 of 29 , Jan 29, 2003
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                          Bob:

                          if you tired of the exchange of ideas concerning this discussion, once you have already made your position clear, but do not wish to be bothered to be asked to defend your postion with stats in a stats analysis group, then maybe this wasn't the forum for you to "...add a few pennies worth of thought on the issue of inter-temporal comparsions of NBA performance..."...

                          Me Now:

                          Actually, I don't tire of an exchange of ideas.  Not in the least.  All that I find tiresome is being obliged to repeat myself

                          no one has yet asked you to repeat yourself, on the contrary if you re-read responses to your postings you have simply been asked a number of times to clarify your statements with numbers (again as this is a stats analysis group) - i.e. show the stats to back up your statements. up and to this last posting you hadn't done that, despite making statements and brandishing them as fact...

                          because you do not find it in your interest to respond to vexing arguments.

                          not in my interest? now that you've finally shown your stats to supposedly back up your statements its going to be fun poking holes in your apparently flawless logic...

                          And the only idea that has been imparted to me by your responses so far is that you have a vested interest in a "sim",

                          then maybe you should show some initiative on your part and read the postings pertinent to this cross-generational discussion that occurred prior to your first posting of 1/2/03. this all started back on 12/10/02 in message 1552 under a topic called "talent dilution". in message 1561 on the same topic the question was raised "....if (only) we could run simulations...on these questions..." of playing teams of different eras against one another....."....

                          but before the topic of even the viability of a simulation was even considered the very next message (1562) contained the statement "...cross-generational team comparisons are subject to so many what-ifs that no one trusts them....". now its fine to state that a sim is subject to "...so many what-ifs...." as that is something we can discuss/debate in a stats analysis group - that's what this group is all about isn't it? after all a simulation is nothing more than an extension of statistical analysis to model a real-life process, similar to modeling the building of widgets in a factory setting or launching a probe into space or any other process that can be quantified...

                          but for someone to blatantly state that "...no one trusts them...", as if that statement had any merit whatsoever (such as did this person review a number of basketball simulations and found them to be lacking, and then discussed this with a number of others who had done just that, or attempted to create a simulation and found it fraught with inconsistencies), reaks of ignorance. if someone was to state that this group member's individual basketball research was totally without merit (or anyone's research for that fact), or that "...no one would trust it...", without that someone even having reviewed that person's research, that too would show ignorance...

                          and you want to use it in completely inappropriate ways,

                          this is your opinion? that to use a computer simulation to model a real-life process is inappropriate? and then to extend that model to go beyond what is actually done in real life to model even more? my now aren't you the researcher........

                          fyi pretty much every process in the real world today, from the fields of sports to medicine to physics to space to whatever, especially in state-of-the-art endeavors, develops computer models based on real world scenarios and then extrapolates those scenarios for predictive purposes, such that further research has a definitive path to follow rather than a blind path.....

                          and it doesn't really matter what anyone says.....

                          once again, on the contrary. what you say does matter, that is why i and others are responding to your postings - but do you expect us to simply take your word for your supposedly factual statements? again this is a stats analysis group and you are just now backing up your statements with some statistical evidence...

                          and i've noticed a tendency in this discussion group for a small minority of the people to make statements and claim them as fact, but when they don't - or can't - back up their statements with some sort of accompanying statistical evidence, they resort to using words like "...absurdly obvious..." to emphasize their point, or make statements like "....it appears that the dead equine will receive another whuppin'...", as if this verification for their opinions....

                          Fair enough, I suppose; it's your toy, play with it as you will.

                          at least i will be looking at your data first - prior to commenting one way or the other on it......i've been asking to see it a number of times....

                          This is not to say that none of your comments could be construed to have been offered in good faith.  Specifically your request for data is perfectly reasonable.  And I am happy to provide it.  See below.  But first repeating the punchline...

                          Me Before:

                          the superiority of the average team in the early 80 to its 60s counterpart  was on the order of 10 to 12 points per game (at a modern game pace).  This is equivalent to how much better the best Bulls team was to the league average.

                          Bob:

                          not sure what these numbers mean or where they are coming from....how did you  arrive at this or derive these numbers?...

                          ...so let me get this straight, you are saying you have statistically come up with a way to show that if the average NBA team of the early 1980s (about 109 pts/g) played an average team from the 1960s (115 pts/g) or early 1960s (almost 116 pts/g), the avg 80s team would beat the average 60s team, on average, by 10-12 points, normalizing for modern times. the 95-96 bulls outscored their opponents that year by just over 12 pts/g. so you are saying the difference in ability to win of an average early 1980s NBA team versus/compared to an average 1960s or early 1960s is the same as the 95-96 bulls to the suns or hornets of 95-96 (.500 teams that year)...

                          is this correct?...

                          Me Now:

                          That is absolutely correct.  More precise numbers below.

                          Me Before:

                          The calculation I referred to was made by computing a measure of offensive (or equivalently defensive) productivity that I called "points per common possession" versus "common possessions per game".  In the former case, the computation is
                          average points scored in the numerator and average common possessions in the denominator.  Common possessions are, by definition and construction, the same for both teams in a particular game (hence attractive for purposes of comparison
                          and analysis) and are basically calculated by subtracting the number of offensive rebounds from the conventionally defined number of possessions a team enjoys in a game.

                          Bob:

                          fine...so fill in the blanks below so we can compare...or show us your numbers that show how you arrived at your result...

                                                    pts/      sec/      pts/
                          year      FG%      g          poss     poss
                          5960      .410     115.3
                          6061      .415     118.1
                          6162      .426     118.8
                          6263      .441     115.3
                          6364      .433     111.0
                          6465      .426     110.6
                          6566      .433     115.5
                          6667      .441     117.4
                          6768      .446     116.6
                          6869      .441     112.3
                          6970      .460     116.7
                          7071      .449     112.4
                          7172      .455     110.2
                          7273      .456     107.6
                          7374      .459     105.7
                          7475      .457     102.3
                          7576      .458     104.3
                          7677      .465     106.5

                                                    pts/      sec/      pts/
                                        FG%   48min   poss      poss
                          7778      .469     107.7    13.4      1.000
                          7879      .485     109.8    13.5      1.029
                          7980      .481     108.5    13.8      1.041   
                          8081      .486     107.5    14.0      1.043
                          8182      .491     107.9    14.1      1.058
                          8283      .485     107.9    13.8      1.037
                          8384      .492     109.2    14.0      1.063
                          8485      .491     110.2    13.9      1.066
                          8586      .487     109.5    13.9      1.059
                          8687      .480     109.2    14.1      1.067
                          8788      .480     107.6    14.3      1.065
                          8889      .477     108.5    14.1      1.062
                          8990      .476     106.3    14.4      1.065
                          9091      .474     105.5    14.5      1.063
                          9192      .472     104.5    14.7      1.067
                          9293      .473     104.5    14.7      1.066
                          9394      .466     101.0    15.0      1.049
                          9495      .466     100.6    15.3      1.069
                          9596      .462      98.8     15.5      1.063
                          9697      .455      96.2     15.8      1.053
                          9798      .450      94.8     15.7      1.036
                          9899      .437      90.9     16.0      1.009
                          9900      .449      96.9     15.3      1.030
                          0001      .443      94.0     15.6      1.020
                          0102      .445      94.8     15.7      1.034

                          DeanO has pointed out that "...this trend looks about right, even if my calculations have slight differences...". so if we are defining offensive productivity as pts/poss, i see similar pts/poss numbers with varying FG% and pts/g and game pace for 77-78
                          thru today. if your number show a different trend for prior to 77-78, lets see them...

                          Me Now:

                          Well, here are my numbers.  They summarize the yearly average team performance in the league.  There are four columns.  The year refers to the end year of the season.  "CP/game" is "Common Possessions per Game".  "P/CP" is "Points per
                          Common Possession".  "P*/CP is the same stat except the points are modified to subtract out the third point of completed three pointers.  Finally, "3pt effect" differences the two previous columns.

                          Year  CP/game  P/CP  P*/CP  3pt effect
                          57      116.4        .856     .856
                          58      124.7        .855     .855
                          59      124.5        .870     .870
                          60      131.2        .879     .879
                          61      132.9        .889     .889
                          62      131.4        .904     .904
                          63      124.5        .926     .926
                          64      121.5        .913     .913
                          65      122.4        .904     .904
                          66      126.1        .916     .916
                          67      126.6        .927     .927
                          68      124.8        .934     .934
                          69      121.7        .923     .923
                          70      122.0        .957     .957
                          71      119.7        .939     .939
                          72      116.4        .946     .946
                          73      114.7        .938     .938
                          74      111.7        .946     .946
                          75      108.5        .946     .946
                          76      109.6        .952     .952
                          77      110.5        .964     .964
                          78      111.0        .977     .977
                          79      109.7      1.005   1.005
                          80      107.3      1.019   1.012   .007 
                          81      105.9      1.021   1.016   .005
                          82      104.7      1.037   1.031   .006
                          83      107.0      1.015   1.010   .005
                          84      105.7      1.042   1.036   .006
                          85      106.1      1.045   1.036   .008
                          86      106.2      1.038   1.029   .009
                          87      105.0      1.047   1.034   .014
                          88      103.5      1.045   1.030   .015
                          89      104.9      1.041   1.021   .020
                          90      102.4      1.045   1.024   .021
                          91      102.0      1.043   1.020   .022
                          92      100.7      1.046   1.021   .025
                          93      100.7      1.045   1.015   .030
                          94        98.7      1.028     .995    .033
                          95        96.8      1.048     .991    .057*
                          96        95.5      1.042     .980    .062*
                          97        93.9      1.032     .967    .064*
                          98        94.2      1.015     .968    .047
                          99        92.7        .987     .939    .048
                          00       96.7      1.008     .957    .050
                          01        95.1        .997     .946    .051
                          02        94.4      1.011     .956    .055

                          Now before discussing trends and repeating the arguments, let me lay out the sources and methods behind these statistics.

                          All data for the "NBA average" are from the Official NBA Guide.  "CP/game" is the following sum of terms (divided by games played): Field Goal Attempts + 0.45 * Free Throw Attempts + 1.05 * Turnovers - 1.045 * Offensive Rebounds.  What this statistic represents again are the number of common possessions between a team and its opponent, or alternatively expressed, the number of continuous possessions - continuous meaning no additional possession is counted on an offensive rebound.  Why the various factors.  Possessions are disposed of as (1) field goal attempts, (2) two shot free throw attempts (three shot free throws are ignored) which I estimate as one half of 90% of all attempts (the other 10% being technicals and attempts after
                          made shots) hence 0.45, (3) turnovers, where a 5% estimate of team turnovers is added, and (4) offensive rebounds, where 4.5% is the estimate of team offensive rebounds.  It should be noted that none of the results are sensitive to the factors chosen which is obvious as the last two terms effectively cancel eachother out.

                          at least for 77-78 thru today, our numbers match fairly closely, and the trends even closer. obviously we are calculating things quite similarly. for benefit of the doubt i'll assume your pre-77-78 estimates are valid for calculating possessions and pts/poss...

                          For the missing turnover and offensive rebound series prior to 1974, I extrapolated using 1974 data.  Specifically, for offensive rebounds, I calculated an offensive rebounding percentage for missed field goal attempts of 28.7 (and assumed a constant 5% value for offensive rebounds of missed final free throws).  This should not be a controversial value as the percentage hovers quite closely about 30%.  And for the turnover series, I assumed a stable relationship of turnovers to field goal attempts and two point field goal attempts, and this value in 1974 was 0.198.  In this case, given the downward trend over time in turnover rate, this value is almost certainly biased low which would have the effect on the data of biasing CP/game down and P/CP up - that is to say exaccerbating the trends I identify.

                          On to the analysis...

                          What are the apparent trends.  Well, I don't think there is any ambiguity on the point that the CP/game series trends downward over time. 

                          agreed....

                          Given that I started off recalling data over the 60s and 70s, let me take '60 and '79 as endpoints to begin the discussion.  Note a drop in game pace from 131.2 to 109.7 possessions per game, a decrease of 15.6%.  And during which time offensive productivity increased 11% (.879 to 1.005).  Put another way, the average team in 1979, playing at its slower pace would be expected to beat the average team of 1960 by 13.82 points per game (.126 P/CP * 109.7 CP/game).

                          so this is your magical brain storm as to why an average 1978-79 team is almost 14 points better than an average 1959-60 team??? you're blatantly stating, based on this one lonely calculation, that:

                          "....the superiority of the average team in the early 80 (in this case 1978-79) to its 60s counterpart was on the order of 10 to 12 points per game (at a modern game pace). This is equivalent to how much better the best Bulls team was to the league average....."

                          you're saying that based on this calculation alone that if the 43-39 san diego clippers or the 38-44 golden state warriors of 1978-79 (closest to avg teams in 78-79) would decimate all of the average teams from 1959-60 by almost 14 pts/g if they played in that year? 14 pts/g on average? 5 of the 8 teams that year only outscored their opponents by +-3 pts/g all year, so thats close to average, so they'd consistently beat these teams like the 72-10 bulls beat an avg team in 1995-96? and teams better than these clippers and warriors would, by virtue of being better than them, beat the 59-60s teams by an even worse margin of average victory?...

                          lets look at this even closer...

                          your numbers also show the offensive productivity of pts/poss in 1966-67 is 0.927, and in 1979-80 is 1.019. so based on these numbers, at a modern pace (in 79-80 of 107.3 CP/game), that offensive productivity increased from 0.927 to 1.019 (difference of 9%), and 0.090 P/CP * 107.3 CP/game is 9.7 pts. so you are saying that an average team from 1979-80 (like the 41-41 houston rockets and 41-41 san antonio spurs) would outscore - on average each game - an average 1966-67 team (cincinnati royals or st louis hawks, both 39-42) by almost 10 pts each game - on average? plus the teams better than the rockets and spurs would beat them - on average - by upwards of 10 or 11 points, and those much better than the rockets and spurs by even 12 or more points per game?....

                          well in 1966-67 the philadelphia 76ers of wilt chamberlain and company only outscored the rest of the league by 9.4 pts/g. you're saying that these .500 teams of 79-80 are 9.7 pts/g better than an average team in 66-67, which would put them on par with the 1966-67 76ers, even slightly better, of wilt chamberlain, luke jackson, hal greer, chet walker, wali jones, and billy cunningham, a team that many would argue is one of the absolute best if not the best teams ever assembled in the history of the NBA, and a team only 13 years earlier in time from 79-80. and not only are you saying that these average teams are slightly better, but that every team in 1979-80 that was above .500, another 9 teams, were thus also better (ostensibly much better) than the 1966-67 philadelphia 76ers?....

                          that would also mean that - based on this one single magical calculation - that in the span of maybe a 5 year period of the late 70s and early 80 (77-78 to 81-82) there'd easily be another 15-20 teams statistically better than the 66-67 76ers (3-4 if not more top teams in the league for each year, well above .500 average teams), one of the greatest teams many would argue that was ever assembled....

                          does anyone in their right mind think that an average team from 79-80 was as good as the 66-67 76ers, and a whole host of teams slightly better than average from 77-78 thru 81-82?? people today debate games between the great celtic teams and great lakers team of the 80s and bulls teams of the 90s against the 66-67 76ers, and you're magical calculation stating its simply no contest?...

                          that would mean that based on your method of determing how much better teams are over eras, that since your pts/poss numbers are even higher after 79-80 (into the decade of the 1980s), that a whole slew of teams, maybe even the vast majority that played over .500 ball in the 1980s, would consistently beat the 66-67 philadelphia 76ers, one of the greatest teams ever, because that magical point difference you concocted would be even greater than 9.7 pts/g because all thru the 1980s the pts/poss was much greater than 1.019, but upwards of 1.030-1.040...

                          and let's take this even a step further.....in 1994-95 the avg pts/poss - based on your numbers - was 1.048, in 98-99 it was 0.987. that's a difference of 0.061. at a CP/game of 92.7 for 98-99 thats .061 * 92.7 = 5.7 point difference, such that based on your magical calculation it shows that based on these calculations of offensive productivity that the average team in 94-95 would beat the average team in 98-99 by 5.7 points, on average, leagues only five years apart! this is the identical calculation method that you have used to show a 78-79 average team was almost 14 points better than an average 59-60 team. if this magical calculation works backwards in time, it must work forward in time, and since offensive productivity shows no trend with game pace in the 1980s and 1990s, so based on your method the average team in 94-95 is only slightly worse than the 2nd and 3rd best teams of 98-99 (utah and portland) who only outscored their opponents by 6.5 and 6.4 pts/g, that in the span of just 5 years, when many players played in both seasons, all of a sudden the league was much worse!...

                          you state that P/CP or pts/poss is an indication of offensive productivity. i agree as it is points scored normalized to a single team possession - it takes game pace out of the equation for determining offensive productivity. our methods of determining this pts/poss are obviously similar, as well as DeanO's, and while yours may show an increase in pts/poss from the early 60s to the late 70s based on estimated values for unknown parameters while game pace consistently decreased, there is absolutely no trend like this from 1978-79 to today. the numbers - your numbers in fact - show this....

                          your numbers show pts/poss of 1.005 in 78-79, and a similar 1.015 (a one percent difference in the two) in 97-98, a time span of a full 20 years! absolutely no difference!  but game pace has decreased from 109.7 CP/game to 94.2 in that same time span, a difference a full 14 % slower game pace - absolutely no trend whatsoever that offensive productivity follows game pace. so while your data may show a trend from the early 60s to the late 70s (with some parameters estimated), it show no trend here. and for you to state that this evidence shows an increase offensive productivity with an increase with game pace, it shows nothing whatsoever over the last 23+ years...

                          pts/poss numbers from 78-79 to 97-98, a 20 year time span, show a range in pts/poss of 1.005-1.048, a difference of 4%. and that varies throughout the 20 year sequence - no trend. even if you look at your 'adjusted" P*/CP from 78-79 to 92-93, the variation is only from 1.005 to 1.036, a variation of just 3 percent while game pace dropped from 109.7 CP/game to 100.7, a difference of an over 8% slower game - thus no trend of game pace at all with pts/poss...

                          And how can this be said to be true?  To repeat the argument that hasn't been addressed: slowing the pace of the game, all else equal, is only compatible theoretically with decreased offensive productivity. 

                          absolute nonsense.......not only has it been addressd, but also debunked.......on the contrary there is no trend whatsoever.....your conclusion/statement is not backed up by your stats.....

                          That there was an increase in offensive productivity must then mean that there was improvement in the way the game was played offensively. 

                          certainly not....offense could have stayed the same and defense weakened to adjust offense upward.......the pts/poss are not absolute numbers like breaking the time of a 100 yard dash but relative numbers of offense versus defense.....the numbers vary not because of some human extreme being reached - again a conclusion not backed up by your stats, but as a variation of a similar process......again one can easily, and i repeat easily, say the defense got worse so as to bring the level of offense up, and the number pts/poss is defined by offense versus defense, not like FT% which is a player versus the basket and not another player...

                          This didn't mean that the '79 players were supermen (though they may have been better athletes).  It means that the offensive "technology" improved. 

                          then based on this convoluted logic the game of 1998-99 (pts/poss of .987) was only being played at the level of 1977-78 (pts/poss 0.977) with seasons like 86-87 (pts/poss of 1.047) and 1994-95 (pts/poss of 1.048) has average teams that could easily beat most teams from 77-78 and 98-99 because of your magical calculation......

                          this reasoning is absolutely porous. the variation of pts/poss is simply a variation of a similar process with the differences being the years being slight. no way are the teams of the mid 1980s 5-6 pts/g better than the late 70s or late 90s.....and your magical calculation has no basis in fact....

                          And what were its intermediate effects: lower turnover rates identified after '73)
                          and higher field goal percentages (apparent throughout).  It also doesn't rule the possibility that defenses improved also, just that on net there was a huge gain for the offenses.

                          Now, Bob, if you can find another explanation for these offsetting trends,

                          no trend whatsoever between pts/poss and game pace (CP/game) after 77-78...

                          and frankly you must if you expect any serious consideration of results from "unadjusted" cross-generational simulations, please provide it.

                          after seeing your "serious" adjustment factor for how much better average teams are from one year to another, i'll stick with unadjusted.....your magical adjustment factor that places average teams from the late 70s and early 80s on par with the great 66-67 76ers and that states that slightly better than average teams from that same time period are actually better teams than the 66-67 76ers tells me just about all i need to know about your methods...

                          There may be one; I just haven't been able to come up with it over the years.  Please try.

                          1966-67 phuladelphia 76ers, 1966-67 philadelphia 76ers, 1966-67 philadelphia 76ers......this is kinda like another posting in this discussion group about different player ratings of sportswriters that did not show shaquille o'neal to be one of the best if not the very best player in the league, and also had andrei kirilenko of the jazz rated 2nd or 3rd best. seeing that told all you needed to know about the rating system...

                          As for the longer-term trends, picking up from the late seventies, the trends should be clear.  The pace of the game continues to fall,

                          yes....

                          and offensive productivity rises and plateaus for a few years in the middle 80s,

                          huh? for a few years? who you kidding? the offensive productivity does not continue to fall, even as game pace does. the offesnive prodictivity numbers (pys/poss) of 97-98 thru 01-02 are simlar to the late 70s and before, but from the early 80s to mid to late 90s the pts/poss numbers vary from a low of 1.015 to 1.048, a difference of just a measly 3%, with no discernible pattern - just fluctuation, which the game pace showing a definite pattern of decreasing.....your number and my numbers both show this....

                          then begins a "mild" decline (that if you hold the view that losing about four points per game is mild - roughly equivalent to home court advantage or, alternatively, half the way from mediocrity to championship status, as I noted before) or alternatively a very significant decline depending on your perspective.

                          To understand this "dilemna" see the last two columns.  They explain the contribution of the three point shot to maintaining "nominal" productivity.  For example, in '02 three point shots raised the P/CP by 0.055 (or rougly 5 points per game). How P*/CP should be interpreted then is as a kind of low estimate of productivity.  Clearly if teams would only be getting two points for a shot behind the three point line, they wouldn't take as many and would instead opt more for more mid-range jumpers. 

                          and shot a higher percentage from 2pt range. pts/poss are pts/poss, the avg FG% for 2pters since 79-80 is .488 (close to .500) and for 3pters is .339 (close to.333). so if players did not take 3pters based on your logic they would be scoring just as much taking 2pters based on the statistical evidence...

                          However, the low estimate might not be that far off.  Consider that in '95 through '97 the three point distance was moved in to not much effect.

                          Whatever the case, the essential is this.  From the mid to late 80's on, offensive productivity has trended downwards along with the pace of the game. 

                          nope....not at all...overall pts/poss varied but remained close to 1.041 - 1.047 in the mid to late 1980s.......

                          In this environment, one could infer that either offenses were getting worse or that defenses were getting better.  And my view is already on record.  The argument again: if you have a quarter century of relentless net offensive progress (and almost certainly some counterveiling defensive progress as well) it seems absurd to argue that come the mid-80's progress came to a screeching halt and was followed by 15 to
                          20 years of, yes, technological retrogression.

                          while our stats are similar, your logic is quite flawed, as is your method for equating teams from different eras...

                          So there is the evidence....gotta run...enjoy your dinner.

                          bob chaikin
                          bchaikin@...


                        • Dean Oliver <deano@rawbw.com>
                          ... philadelphia ... group about ... shaquille o neal ... and also had ... told all you ... Actually, that wasn t a sportswriter rating. That was Jeff
                          Message 12 of 29 , Jan 30, 2003
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                            --- In APBR_analysis@yahoogroups.com, bchaikin@a... wrote:
                            > 1966-67 phuladelphia 76ers, 1966-67 philadelphia 76ers, 1966-67
                            philadelphia
                            > 76ers......this is kinda like another posting in this discussion
                            group about
                            > different player ratings of sportswriters that did not show
                            shaquille o'neal
                            > to be one of the best if not the very best player in the league,
                            and also had
                            > andrei kirilenko of the jazz rated 2nd or 3rd best. seeing that
                            told all you
                            > needed to know about the rating system...

                            Actually, that wasn't a sportswriter rating. That was Jeff Sagarin's
                            mathematical method (along with Wayne Winston, a business prof). The
                            method is pretty good, looking at how well different combinations of
                            players do, who they play against, then isolating each player's
                            contribution, but the results are highly suspect and I continue to
                            wonder why. I think I understand but it's complex.

                            Sagarin does have a public email that I just found. I'd be curious
                            to ask him about it...

                            DeanO
                          • schtevie2003 <schtevie@hotmail.com>
                            Bob, I am heartened that at long last you are finally beginning to understand the empirical history involved (though for some reason the 80s to present still
                            Message 13 of 29 , Jan 30, 2003
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                              Bob,

                              I am heartened that at long last you are finally beginning to
                              understand the empirical history involved (though for some
                              reason the 80s to present still confuse you). I am also tickled
                              that at long last you certainly do understand the essence of my
                              magical calculation. Soon, I trust, as your comprehension
                              improves, the term magical will be replaced by elegant, as that is
                              more apropos. However, that moment awaits your
                              understanding of the simple logic which drives the inference,
                              and about which I should restate again that I am not emotionally
                              or financially beholden to its correctness. (Please find an
                              alternative to its conclusions; I will be just as happy in this case -
                              well maybe not quite.) I still have hope for you, so keep trying.

                              But first a few words on the discussion itself, its context and the
                              decorum of participants. As far as I can tell, no one participating
                              in this group is hostile to simulations being a useful tool for
                              analysis; I most certainly am not and have always enjoyed your
                              presentation of facts regarding your product - though now I have
                              growing questions of the substance of your magical sim. That
                              said, your penchant for aggression and lack of good faith in
                              addressing the concerns of others is nothing but offputting.
                              Case in point: the initial point I was making regarding the clear
                              and dominant superiority of 80s teams over 60s teams was
                              conditional on stipulated facts. It seems to me the courteous
                              and productive way to respond is to say "OK let's stipulate the
                              facts and address the theoretical argument, with the ultimate
                              factual (as opposed to theoretical) conclusion dependent on the
                              presentation of facts," as opposed to instead offering irrelevant
                              data series and condescending remarks. But whatever...on to
                              the substance.

                              First, here again, as they invoked no real controversy, are the
                              data and definitions I provided.

                              (The year refers to the end year of the season. "CP/game" is
                              "Common Possessions per Game". "P/CP" is "Points per
                              Common Possession". "P*/CP is the same stat except the
                              points are modified to subtract out the third point of completed
                              three pointers. Finally, "3pt effect" differences the two previous
                              columns.)

                              > Year CP/game P/CP P*/CP 3pt effect
                              > 57 116.4 .856 .856
                              > 58 124.7 .855 .855
                              > 59 124.5 .870 .870
                              > 60 131.2 .879 .879
                              > 61 132.9 .889 .889
                              > 62 131.4 .904 .904
                              > 63 124.5 .926 .926
                              > 64 121.5 .913 .913
                              > 65 122.4 .904 .904
                              > 66 126.1 .916 .916
                              > 67 126.6 .927 .927
                              > 68 124.8 .934 .934
                              > 69 121.7 .923 .923
                              > 70 122.0 .957 .957
                              > 71 119.7 .939 .939
                              > 72 116.4 .946 .946
                              > 73 114.7 .938 .938
                              > 74 111.7 .946 .946
                              > 75 108.5 .946 .946
                              > 76 109.6 .952 .952
                              > 77 110.5 .964 .964
                              > 78 111.0 .977 .977
                              > 79 109.7 1.005 1.005
                              > 80 107.3 1.019 1.012 .007
                              > 81 105.9 1.021 1.016 .005
                              > 82 104.7 1.037 1.031 .006
                              > 83 107.0 1.015 1.010 .005
                              > 84 105.7 1.042 1.036 .006
                              > 85 106.1 1.045 1.036 .008
                              > 86 106.2 1.038 1.029 .009
                              > 87 105.0 1.047 1.034 .014
                              > 88 103.5 1.045 1.030 .015
                              > 89 104.9 1.041 1.021 .020
                              > 90 102.4 1.045 1.024 .021
                              > 91 102.0 1.043 1.020 .022
                              > 92 100.7 1.046 1.021 .025
                              > 93 100.7 1.045 1.015 .030
                              > 94 98.7 1.028 .995 .033
                              > 95 96.8 1.048 .991 .057*
                              > 96 95.5 1.042 .980 .062*
                              > 97 93.9 1.032 .967 .064*
                              > 98 94.2 1.015 .968 .047
                              > 99 92.7 .987 .939 .048
                              > 00 96.7 1.008 .957 .050
                              > 01 95.1 .997 .946 .051
                              > 02 94.4 1.011 .956 .055

                              (Now before discussing trends and repeating the arguments, let
                              me lay out the sources and methods behind these statistics. All
                              data for the "NBA average" are from the Official NBA Guide.
                              "CP/game" is the following sum of terms (divided by games
                              played): Field Goal Attempts + 0.45 * Free Throw Attempts + 1.05
                              * Turnovers - 1.045 * Offensive Rebounds. What this statistic
                              represents again are the number of common possessions
                              between a team and its opponent, or alternatively expressed, the
                              number of continuous possessions - continuous meaning no
                              additional possession is counted on an offensive rebound. Why
                              the various factors. Possessions are disposed of as (1) field
                              goal attempts, (2) two shot free throw attempts (three shot free
                              throws are ignored) which I estimate as one half of 90% of all
                              attempts (the other 10% being technicals and attempts after
                              made shots) hence 0.45, (3) turnovers, where a 5% estimate of
                              team turnovers is added, and (4) offensive rebounds, where
                              4.5% is the estimate of team offensive rebounds. It should be
                              noted that none of the results are sensitive to the factors chosen
                              which is obvious as the last two terms effectively cancel each
                              other out.)

                              (For the missing turnover and offensive rebound series prior to
                              1974, I extrapolated using 1974 data. Specifically, for offensive
                              rebounds, I calculated an offensive rebounding percentage for
                              missed field goal attempts of 28.7 (and assumed a constant 5%
                              value for offensive rebounds of missed final free throws). This
                              should not be a controversial value as the percentage hovers
                              quite closely about 30%. And for the turnover series, I assumed
                              a stable relationship of turnovers to field goal attempts and two
                              point field goal attempts, and this value in 1974 was 0.198. In
                              this case, given the downward trend over time in turnover rate,
                              this value is almost certainly biased low which would have the
                              effect on the data of biasing CP/game down and P/CP up - that is
                              to say exaccerbating the trends I identify.)

                              So I began my discussion of the data with an actual calculation
                              of my original recollection, to which Bob responds....

                              ...so this is your magical brain storm as to why an average
                              1978-79 team is almost 14 points better than an average
                              1959-60 team??? you're blatantly stating, based on this one
                              lonely calculation, that:

                              "....the superiority of the average team in the early 80 (in this
                              case 1978-79) to its 60s counterpart was on the order of 10 to 12
                              points per game (at a modern game pace). This is equivalent to
                              how much better the best Bulls team was to the league
                              average....."

                              I say again: yes, yes, and yes, certainly to a first approximation
                              and absent any introduced counter-argument.

                              Bob then goes on to offer myriad calculations based on "this one
                              lonely calculation" comparing "undeniably" great teams with
                              "undeniably" average teams, with the rhetorical weight of his
                              preconceptions and anecdotes (but no statistics or even perish
                              the thought philosophy!) designed to persuade that the inference
                              behind the calculation (not the calculation itself) must, just must
                              be wrong.

                              So here we begin. What is this one lonely calculation? It is in
                              fact the average performance of the league. I suppose I must
                              agree, it is lonely, singular is a better word, in its breadth. But it
                              is the bottom line; there is no other for the issue in question.

                              That said, let me state unequivocally what I view the trends to be,
                              and after, I will go step by step through the chain of inference
                              which leads to the contentious conclusions. The trend in game
                              pace is not at issue, the game has slowed continuously over the
                              past 30 plus years. Agreed. There is, however, an apparent
                              controversy over the trends in offensive productivity (that there is
                              is somewhat mind-boggling to me - well not really when I think
                              about it.)

                              Points per common possession increase from 1960 (.879) and
                              come to a somewhat flat peak around 1984 or 1985 (1.045)
                              thereafter descending almost without exception to 2000. That
                              you cannot see this, Bob, I can only explain from reading your
                              remarks in two ways (besides the more cynical interpretation).
                              First, you apparently don't understand the importance of the
                              increasing usage of the 3 point shot in obscuring the series
                              trends. The three pointer is an "ad hoc" rule change which
                              directly biases scoring upwards (by design of course) and the
                              shallow learning curve on how to employ the shot efficiently
                              makes the plateau merely apparent, not real. Second, and more
                              gratuitously, you ignore the particular bias of moving the three
                              point line in between 1995 and 1997. These effects on the
                              series are clear and were precisely why they were presented.
                              And finally, you support your notion that there are no trends in
                              productivity since 1979 (though again this is not a meaningful
                              endpoint for discussion) by arguing that the deviations in
                              productivity within the period are somehow not significant. This
                              view is simply untenable. Taking a maximum rise of about 0.04
                              points per common possession (between 1979 and 1985) this
                              translates to an average increase - I would say improvement - of
                              about 4 points per game. Yes, four is a small number compared
                              to 13.5 or 1,000,003, but in the context of NBA basketball, the
                              margin is huge.

                              But I suppose that you would say that it begs the question. Is it
                              in fact an improvement or does it - according to your belief - imply
                              nothing, with the quality of the league on average ever
                              unchanging?

                              Perhaps now, before re-explaining the argument as to why the
                              game has decidedly improved over time, it would be worthwhile,
                              for the purpose of contrast, to flesh out the implication of your
                              view (yes, I know, it is my interpretation of your view) in the
                              context of the evidence (even allowing for our divergent views of
                              latter-day trends.) In Bob's world, a change in measured
                              offensive productivity means nothing, the NBA resides in a state
                              of God-given equipoise. So offensive productivity increases 15%
                              over 25 years. Guess what? That just happens to be a 7.5%
                              increase in true offensive productivity and a 7.5% decrease in
                              true defensive productivity. (And why again did defenses get
                              worse?) Same story for an increase of 1%, 2%, 3%, 4%, 5%, 6%,
                              7%...Pick a number; it doesn't matter; let's just run the "sim" with
                              actual numbers!

                              The question we return to then is how one should interpret
                              changes in offensive (equivalently defensive) productivity that are
                              observed in the data, dramatic or otherwise. But now, and note
                              the change of subject, the discussion is strictly about theoretical
                              issues; it has nothing to do with any particular numbers. Here
                              we go. Now pay attention, and please feel free to respond
                              directly to what is argued here, no side-stepping the issues, no
                              introduction of irrelevant topics.

                              Suppose we see a change, an increase in average offensive
                              productivity or alternatively a decrease in average defensive
                              productivity. How can we say whether offenses are getting better
                              or that defenses are getting worse. Absent any additional
                              information, we cannot. Noting that turnover rates drop is
                              suggestive, it would appear that offenses are getting better at
                              protecting the ball, but that does not negate the theoretical
                              justification of arguing that maybe defenses are simply
                              increasingly inept at stealing the ball. So appeals to
                              intermediate statistics yield no resolution to the argument.

                              Enter the "pace of game" variable. This data series has the
                              property in certain instances (not in all instances) to identify
                              whether or not observed changes in offensive productivity are net
                              improvements. In particular, when the pace of the game slows,
                              any increase in offensive productivity represents a net
                              improvement in offensive play. Why? The theory is this.

                              All else equal, if the average pace of the game slows, it means
                              that offensive productivity must fall. Why? If the time of the
                              average possession is increasing, it means either that there are
                              fewer fast-breaks in the mix or that within half-court offenses
                              more time elapses before a shot is taken. The necessary
                              consequence of these two possible outcomes is the same,
                              offensive productivity must fall. In the first instance, fewer
                              fast-breaks mean that on-average higher percentage shots are
                              being eliminated. In the second instance, longer half-court
                              possessions mean that the quality of shot that was previously
                              available earlier in the possession are not available and more
                              time is taken to yield, in expectation, at least no better of a shot.

                              (Understanding this, we can also note a circumstance where the
                              pace of game variable cannot be used to identify net progress in
                              the offensive productivity variable. When offensive productivity
                              falls along with the pace of the game - what happened from the
                              mid-'80s onward - according to the theory it can mean that either
                              defenses got on net better, with offenses also possibly
                              improving, or it can mean that offenses simply got worse. In the
                              instance of the actual NBA history, I don't think the latter
                              interpretation is justified, and as suggestive evidence consider
                              the growing importance of the three point shot; what to me is
                              clearly incremental progress toward a newly optimal strategy -
                              hardly the hallmark of technological retrogression.)

                              Thus, if a falling game pace is observed and an increase in
                              offensive productivity is observed, the latter is necessarily a net
                              gain in offensive productivity. The true improvement in offense
                              might be higher still, compensated by an improvement in
                              defense, but the actual statistic represents a lower bound on
                              offensive improvement.

                              Bob, that is the theoretical argument. It is what must be
                              responded to on theoretical grounds if you are serious in your
                              objections to the empirical conclusions offered. And to date the
                              theory has not been addressed by you. Fond recollections of the
                              '67 Sixers are insufficient.

                              More generally though, in your quest to offer a serious objection
                              to the overall conclusion -besides finding a flaw in the magical
                              theoretical argument - let me try to help you a bit by providing a
                              possible category for you to consider. Perhaps there are some
                              rules change (akin to the introduction of the three point shot) that
                              affect the actual interpretation of the data over the sweep of
                              history considered. After all, see how the misinterpretation of the
                              three point data flummoxed you? Perhaps there are rule
                              changes, slowly adapted to, that seen in proper perspective
                              would attenuate the huge gains in offensive productivity from the
                              late '60s to the mid-'80s. Identifying these would put the
                              magnitude, but almost certainly not the existance, of the net
                              offensive improvement in question. Anyway, think a little before
                              you respond. And, of course, please provide data.

                              And as always, thank you for your consideration.
                            • bchaikin@aol.com
                              Given that I started off recalling data over the 60s and 70s, let me take 60 and 79 as endpoints to begin the discussion. Note a drop in game pace from 131.2
                              Message 14 of 29 , Jan 31, 2003
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                                Given that I started off recalling data over the 60s and 70s, let me take '60 and '79 as endpoints to begin the discussion. Note a drop in game pace from 131.2 to 109.7
                                possessions per game, a decrease of 15.6%. And during which time offensive productivity increased 11% (.879 to 1.005). Put another way, the average team in 1979, playing at its slower pace would be expected to beat the average team of 1960 by 13.82 points per game (.126 P/CP * 109.7 CP/game).

                                ...so this is your magical brain storm as to why an average 1978-79 team is almost 14 points better than an average 1959-60 team??? you're blatantly stating, based on this one lonely calculation, that:

                                "....the superiority of the average team in the early 80 (in this case 1978-79) to its 60s counterpart was on the order of 10 to 12 points per game (at a modern game pace). This is equivalent to how much better the best Bulls team was to the league
                                average....."

                                I say again: yes, yes, and yes, certainly to a first approximation and absent any introduced counter-argument.

                                your 1959-60 pts/poss is .879. your 1978-79 pts/poss is 1.005. you are saying that:

                                1 - (.879)/(1.005) = 0.126 difference in pts/poss between 59-60 and 78-79...

                                you are then multiplying this pts/poss difference by the 78-79 game pace:

                                0.126 x 109.7 = 13.82 pts/g

                                and you are then stating that because of this percent difference that since these pts/poss numbers are the average for their respective season, that an average team in 78-79 would beat an average team in 59-60 by almost 14 points....

                                but like professor morbius in the forbidden planet, you are clueless...

                                this calculation of yours is absolutely meaningless, because you fail to realize that pts/poss, while a measure of "offensive productivity", is at the same time a measure of what the defense allows per possession. you are measuring simply one side of the ball, and looking only at offense, and your calculation assumes that the defensive pts/poss remained the same over that time...

                                pts/poss scored is a relative number, what the offense scores against the defense on average, or what the defense allows the offense to score on average. it is a relative number stating the "balance" between what the offense produces and what the defense gives up...

                                in 59-60 defenses allowed only 0.879 pts/poss, as compared to in 78-79 defenses allowing 1.005 pts/poss. no matter how you want to look at it, a defense giving up just 0.879 pts/poss is "better" than a defense that gives up 1.005 pts/poss - in any game where two teams each have the same number of possessions, the team giving up the least amount of pts/poss will win. thus the avg team in 59-60, based on your meaningless logic, states that 59-60 had the better avg defensive teams...

                                stating that an offensive productivity of 1.005 in 78-79 is better than 0.879 in 59-60 is exactly the same as saying a defense allowing 1.005 pts/poss in 78-79 is worse than a defense allowing just 0.879 pts/poss in 59-60...

                                this is exactly the same arguement you are using to say teams of 78-79 are better than teams of 59-60, simply because the avg team pts/poss is greater, 1.005 to 0.879. it has no basis in fact. using your formula one can say the teams of 59-60 are 13.82 better on defense than teams of 78-79, and thus if they played the avg 59-60 team would defeat the avg 78-79 team by that 13.82 pts/g, actually even more because the game pace was greater in 59-60...

                                0.126 x 131.2 = 16.5 pts/g

                                thus an avg 59-60 team, because of its "better" defense, would outscore an avg 78-79 team by 16.5 pts/g, normalized for the 59-60 game pace. this manipulation of the numbers is worthless...

                                a completely meaningless calculation that has no basis in fact....

                                bob chaikin
                                bchaikin@...






                              • schtevie2003 <schtevie@hotmail.com>
                                Bob, I read your posting, shaking my head in disbelief. What could possibly be your motivation for not responding to any of the substantive points in the
                                Message 15 of 29 , Feb 3, 2003
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                                  Bob, I read your posting, shaking my head in disbelief. What
                                  could possibly be your motivation for not responding to any of the
                                  substantive points in the previous posting? They were not hard
                                  to identify in the text; I pointed them out as they arose, inviting a
                                  response, noting that for an alternative interpretation of the data
                                  to prevail that these were the relevant points at issue. But a
                                  complete lack of response is what you offered. In fact, all you
                                  posted was a numerical illustration of the problem that I initially
                                  presented (way back when)! And that problem is that one cannot
                                  identify progress or regress based on movements in average
                                  offensive (equivalently defensive) productivity alone.
                                  Congratulations on your having mastered the first sentence of
                                  paragraph one, now proceed onwards!

                                  I am left with the belief that the only plausible answer for your
                                  lack of responsiveness (if not the rudeness) is that you are
                                  entirely cynical. (After all, your stated profession demands in
                                  training that you have the intellect to understand the type of
                                  arguments presented - based as they are on simplest math and
                                  logic. And you have shown yourself to be very dogged pursuing
                                  evidence - all that S.J. Gould stuff - when you think you have a
                                  case.) I can only think that you have seen the error of your ways
                                  and are hoping no one else has (?) and are blustering to the
                                  end, hoping that I will tire of repeating the argument - and
                                  imploring you to respond - thereby taking some odd comfort in
                                  being the last one to opine. Such an approach has its
                                  consequences however and ones I would be very concerned
                                  about them if I were you. In particular, your credibility erodes. At
                                  best (?) one is left with the misimpression that you lack a certain
                                  acuity. At worst is the inference that you lack trustworthiness,
                                  being willing to obfuscate for the purposes of protecting a vested
                                  interest.

                                  So here we go again - this time with much greater brevity.

                                  To be interpreted: the rise (to the mid-80s) and fall (thereafter) of
                                  offensive productivity (well actually just the rise, but the fall - I
                                  presume - is at least finally admitted to as being fact?)

                                  Interpretation offered: falling game pace identifies observed
                                  increase is offensive productivity as a net (that is lower bound)
                                  improvement in offensive "technology" (that is distinct from player
                                  height, strength, or athleticism) as opposed to a decrease in
                                  defensive "technology".

                                  Basis of inference: Possessions by definition consist exclusively
                                  of fast-breaks and non-fast-breaks (that is half-court set
                                  offenses). By definition fast-breaks take less time and yield
                                  higher points per possession. Thus, all else equal (READ: IF
                                  THERE HAS BEEN NO CHANGE IN OFFENSIVE
                                  "TECHNOLOGY") if the game slows, this means that by
                                  definition there are either fewer fast-breaks or longer half-court
                                  possessions. In either of these two instances, the implication is
                                  that average offensive productivity falls. THUS, THERE MUST
                                  HAVE BEEN A CHANGE IN OFFENSIVE TECHNOLOGY.

                                  Bob, there is the argument. Deal with it (and all the better if no
                                  gratuitous insults are offered) or just sit down.

                                  Oh yes, one final thing. If behind your inability to deal with the
                                  arguments is your inquietude with the jarring statistical
                                  conclusion (12 to 14 points, blah, blah, blah) perhaps it is
                                  comforting to know that I share it to a certain degree, but absent
                                  ameliorating explanations (or some error of my ways) I feel
                                  obliged to accept the calculation as is.

                                  That said, it would be nice if there were some other evidence of a
                                  time machine sort that could to some degree corroborate the
                                  logical inference above. And perhaps (only perhaps) there is.
                                  Consider two cases:

                                  1. Teams that went retro to their detriment (thanks to Mike G. for
                                  the idea). As a possible (and I only say possible) case in point,
                                  the '90 Nuggets became the '91 Nutties and increased their
                                  possessions per game by 8.4 and dropped their points per
                                  possession by .033. Now, if one looks at these changes and
                                  links them to movements in the league averages these are
                                  equivalent to going back in time from 1990 to 1978 in the former
                                  case and to between '78 and '79 in the latter. Now, whether any
                                  ultimately persuasive evidence can ever be gleaned from looking
                                  at the basketcases on the NBA over time is not clear to me, but
                                  it's a thought in progress.

                                  2. More persuasive to me now is a reasoned interpretation of
                                  the performance of NBA All-Stars in Olympic/World Competition.
                                  Witness how over a mere decade, the rest of the world went from
                                  being whipping boys to being serious competitors. (Sorry, no
                                  hard data on average victory margins of European and South
                                  American elite vs. NBA, but it must show a movement of at least
                                  10 points per game on average.) So what would the analogy be?

                                  In the case of the NBA history in question, the presumption is
                                  that greatness is greatness no matter when, and it is
                                  unreasonable to assume improvement, especially dramatic
                                  improvement, over relatively short periods of time. As in "are you
                                  trying to tell me that the average NBA team in the early 90s was
                                  as good or better than the 67 Warriors, clearly one of the greatest
                                  teams ever?"

                                  Against this we have witnessed just such dramatic improvement
                                  against relatively constant NBA talent in a not-too-distantly
                                  related theater - though arguably it can in large measure be
                                  attributed to improvements in foreign talent as well as in
                                  organization (though wasn't the presumption that talent
                                  increases weren't that plausible either?)

                                  The tentative upshot: massive changes can happen in relatively
                                  short periods of time, to the surprise and sadness of many.

                                  ***************

                                  --- In APBR_analysis@yahoogroups.com, bchaikin@a... wrote:
                                  >
                                  > Given that I started off recalling data over the 60s and 70s, let
                                  me take '60
                                  > and '79 as endpoints to begin the discussion. Note a drop in
                                  game pace from
                                  > 131.2 to 109.7
                                  > possessions per game, a decrease of 15.6%. And during
                                  which time offensive
                                  > productivity increased 11% (.879 to 1.005). Put another way,
                                  the average team
                                  > in 1979, playing at its slower pace would be expected to beat
                                  the average
                                  > team of 1960 by 13.82 points per game (.126 P/CP * 109.7
                                  CP/game).
                                  >
                                  > ...so this is your magical brain storm as to why an average
                                  1978-79 team is
                                  > almost 14 points better than an average 1959-60 team???
                                  you're blatantly
                                  > stating, based on this one lonely calculation, that:
                                  >
                                  > "....the superiority of the average team in the early 80 (in this
                                  case
                                  > 1978-79) to its 60s counterpart was on the order of 10 to 12
                                  points per game
                                  > (at a modern game pace). This is equivalent to how much
                                  better the best Bulls
                                  > team was to the league
                                  > average....."
                                  >
                                  > I say again: yes, yes, and yes, certainly to a first approximation
                                  and absent
                                  > any introduced counter-argument.
                                  >
                                  > your 1959-60 pts/poss is .879. your 1978-79 pts/poss is 1.005.
                                  you are saying
                                  > that:
                                  >
                                  > 1 - (.879)/(1.005) = 0.126 difference in pts/poss between 59-60
                                  and 78-79...
                                  >
                                  > you are then multiplying this pts/poss difference by the 78-79
                                  game pace:
                                  >
                                  > 0.126 x 109.7 = 13.82 pts/g
                                  >
                                  > and you are then stating that because of this percent difference
                                  that since
                                  > these pts/poss numbers are the average for their respective
                                  season, that an
                                  > average team in 78-79 would beat an average team in 59-60
                                  by almost 14
                                  > points....
                                  >
                                  > but like professor morbius in the forbidden planet, you are
                                  clueless...
                                  >
                                  > this calculation of yours is absolutely meaningless, because
                                  you fail to
                                  > realize that pts/poss, while a measure of "offensive
                                  productivity", is at the
                                  > same time a measure of what the defense allows per
                                  possession. you are
                                  > measuring simply one side of the ball, and looking only at
                                  offense, and your
                                  > calculation assumes that the defensive pts/poss remained the
                                  same over that
                                  > time...
                                  >
                                  > pts/poss scored is a relative number, what the offense scores
                                  against the
                                  > defense on average, or what the defense allows the offense to
                                  score on
                                  > average. it is a relative number stating the "balance" between
                                  what the
                                  > offense produces and what the defense gives up...
                                  >
                                  > in 59-60 defenses allowed only 0.879 pts/poss, as compared
                                  to in 78-79
                                  > defenses allowing 1.005 pts/poss. no matter how you want to
                                  look at it, a
                                  > defense giving up just 0.879 pts/poss is "better" than a
                                  defense that gives
                                  > up 1.005 pts/poss - in any game where two teams each have
                                  the same number of
                                  > possessions, the team giving up the least amount of pts/poss
                                  will win. thus
                                  > the avg team in 59-60, based on your meaningless logic,
                                  states that 59-60 had
                                  > the better avg defensive teams...
                                  >
                                  > stating that an offensive productivity of 1.005 in 78-79 is better
                                  than 0.879
                                  > in 59-60 is exactly the same as saying a defense allowing
                                  1.005 pts/poss in
                                  > 78-79 is worse than a defense allowing just 0.879 pts/poss in
                                  59-60...
                                  >
                                  > this is exactly the same arguement you are using to say teams
                                  of 78-79 are
                                  > better than teams of 59-60, simply because the avg team
                                  pts/poss is greater,
                                  > 1.005 to 0.879. it has no basis in fact. using your formula one
                                  can say the
                                  > teams of 59-60 are 13.82 better on defense than teams of
                                  78-79, and thus if
                                  > they played the avg 59-60 team would defeat the avg 78-79
                                  team by that 13.82
                                  > pts/g, actually even more because the game pace was greater
                                  in 59-60...
                                  >
                                  > 0.126 x 131.2 = 16.5 pts/g
                                  >
                                  > thus an avg 59-60 team, because of its "better" defense, would
                                  outscore an
                                  > avg 78-79 team by 16.5 pts/g, normalized for the 59-60 game
                                  pace. this
                                  > manipulation of the numbers is worthless...
                                  >
                                  > a completely meaningless calculation that has no basis in
                                  fact....
                                  >
                                  > bob chaikin
                                  > bchaikin@b...
                                • Dean Oliver <deano@rawbw.com>
                                  All right! For whatever reason there is a disconnect here on this topic. Let s hold off a while on this train of thought and converse on some other things.
                                  Message 16 of 29 , Feb 3, 2003
                                  • 0 Attachment
                                    All right! For whatever reason there is a disconnect here on this
                                    topic. Let's hold off a while on this train of thought and converse
                                    on some other things. It's getting to some rather uninformative long-
                                    winded counterproductive stuff.

                                    So let's not talk about this thing for a month or so. Hopefully some
                                    of these other tracks will address other issues that may lead to
                                    productive discussion...LATER!!!

                                    DeanO
                                    Moderator

                                    --- In APBR_analysis@yahoogroups.com, "schtevie2003 <schtevie@h...>"
                                    <schtevie@h...> wrote:
                                    > Bob, I read your posting, shaking my head in disbelief. What
                                    > could possibly be your motivation for not responding to any of the
                                    > substantive points in the previous posting? They were not hard
                                    > to identify in the text; I pointed them out as they arose, inviting
                                    a
                                    > response, noting that for an alternative interpretation of the data
                                    > to prevail that these were the relevant points at issue. But a
                                    > complete lack of response is what you offered. In fact, all you
                                    > posted was a numerical illustration of the problem that I initially
                                    > presented (way back when)! And that problem is that one cannot
                                    > identify progress or regress based on movements in average
                                    > offensive (equivalently defensive) productivity alone.
                                    > Congratulations on your having mastered the first sentence of
                                    > paragraph one, now proceed onwards!
                                    >
                                    > I am left with the belief that the only plausible answer for your
                                    > lack of responsiveness (if not the rudeness) is that you are
                                    > entirely cynical. (After all, your stated profession demands in
                                    > training that you have the intellect to understand the type of
                                    > arguments presented - based as they are on simplest math and
                                    > logic. And you have shown yourself to be very dogged pursuing
                                    > evidence - all that S.J. Gould stuff - when you think you have a
                                    > case.) I can only think that you have seen the error of your ways
                                    > and are hoping no one else has (?) and are blustering to the
                                    > end, hoping that I will tire of repeating the argument - and
                                    > imploring you to respond - thereby taking some odd comfort in
                                    > being the last one to opine. Such an approach has its
                                    > consequences however and ones I would be very concerned
                                    > about them if I were you. In particular, your credibility erodes.
                                    At
                                    > best (?) one is left with the misimpression that you lack a certain
                                    > acuity. At worst is the inference that you lack trustworthiness,
                                    > being willing to obfuscate for the purposes of protecting a vested
                                    > interest.
                                    >
                                    > So here we go again - this time with much greater brevity.
                                    >
                                    > To be interpreted: the rise (to the mid-80s) and fall (thereafter)
                                    of
                                    > offensive productivity (well actually just the rise, but the fall -
                                    I
                                    > presume - is at least finally admitted to as being fact?)
                                    >
                                    > Interpretation offered: falling game pace identifies observed
                                    > increase is offensive productivity as a net (that is lower bound)
                                    > improvement in offensive "technology" (that is distinct from player
                                    > height, strength, or athleticism) as opposed to a decrease in
                                    > defensive "technology".
                                    >
                                    > Basis of inference: Possessions by definition consist exclusively
                                    > of fast-breaks and non-fast-breaks (that is half-court set
                                    > offenses). By definition fast-breaks take less time and yield
                                    > higher points per possession. Thus, all else equal (READ: IF
                                    > THERE HAS BEEN NO CHANGE IN OFFENSIVE
                                    > "TECHNOLOGY") if the game slows, this means that by
                                    > definition there are either fewer fast-breaks or longer half-court
                                    > possessions. In either of these two instances, the implication is
                                    > that average offensive productivity falls. THUS, THERE MUST
                                    > HAVE BEEN A CHANGE IN OFFENSIVE TECHNOLOGY.
                                    >
                                    > Bob, there is the argument. Deal with it (and all the better if no
                                    > gratuitous insults are offered) or just sit down.
                                    >
                                    > Oh yes, one final thing. If behind your inability to deal with the
                                    > arguments is your inquietude with the jarring statistical
                                    > conclusion (12 to 14 points, blah, blah, blah) perhaps it is
                                    > comforting to know that I share it to a certain degree, but absent
                                    > ameliorating explanations (or some error of my ways) I feel
                                    > obliged to accept the calculation as is.
                                    >
                                    > That said, it would be nice if there were some other evidence of a
                                    > time machine sort that could to some degree corroborate the
                                    > logical inference above. And perhaps (only perhaps) there is.
                                    > Consider two cases:
                                    >
                                    > 1. Teams that went retro to their detriment (thanks to Mike G. for
                                    > the idea). As a possible (and I only say possible) case in point,
                                    > the '90 Nuggets became the '91 Nutties and increased their
                                    > possessions per game by 8.4 and dropped their points per
                                    > possession by .033. Now, if one looks at these changes and
                                    > links them to movements in the league averages these are
                                    > equivalent to going back in time from 1990 to 1978 in the former
                                    > case and to between '78 and '79 in the latter. Now, whether any
                                    > ultimately persuasive evidence can ever be gleaned from looking
                                    > at the basketcases on the NBA over time is not clear to me, but
                                    > it's a thought in progress.
                                    >
                                    > 2. More persuasive to me now is a reasoned interpretation of
                                    > the performance of NBA All-Stars in Olympic/World Competition.
                                    > Witness how over a mere decade, the rest of the world went from
                                    > being whipping boys to being serious competitors. (Sorry, no
                                    > hard data on average victory margins of European and South
                                    > American elite vs. NBA, but it must show a movement of at least
                                    > 10 points per game on average.) So what would the analogy be?
                                    >
                                    > In the case of the NBA history in question, the presumption is
                                    > that greatness is greatness no matter when, and it is
                                    > unreasonable to assume improvement, especially dramatic
                                    > improvement, over relatively short periods of time. As in "are you
                                    > trying to tell me that the average NBA team in the early 90s was
                                    > as good or better than the 67 Warriors, clearly one of the greatest
                                    > teams ever?"
                                    >
                                    > Against this we have witnessed just such dramatic improvement
                                    > against relatively constant NBA talent in a not-too-distantly
                                    > related theater - though arguably it can in large measure be
                                    > attributed to improvements in foreign talent as well as in
                                    > organization (though wasn't the presumption that talent
                                    > increases weren't that plausible either?)
                                    >
                                    > The tentative upshot: massive changes can happen in relatively
                                    > short periods of time, to the surprise and sadness of many.
                                    >
                                    > ***************
                                    >
                                    > --- In APBR_analysis@yahoogroups.com, bchaikin@a... wrote:
                                    > >
                                    > > Given that I started off recalling data over the 60s and 70s, let
                                    > me take '60
                                    > > and '79 as endpoints to begin the discussion. Note a drop in
                                    > game pace from
                                    > > 131.2 to 109.7
                                    > > possessions per game, a decrease of 15.6%. And during
                                    > which time offensive
                                    > > productivity increased 11% (.879 to 1.005). Put another way,
                                    > the average team
                                    > > in 1979, playing at its slower pace would be expected to beat
                                    > the average
                                    > > team of 1960 by 13.82 points per game (.126 P/CP * 109.7
                                    > CP/game).
                                    > >
                                    > > ...so this is your magical brain storm as to why an average
                                    > 1978-79 team is
                                    > > almost 14 points better than an average 1959-60 team???
                                    > you're blatantly
                                    > > stating, based on this one lonely calculation, that:
                                    > >
                                    > > "....the superiority of the average team in the early 80 (in this
                                    > case
                                    > > 1978-79) to its 60s counterpart was on the order of 10 to 12
                                    > points per game
                                    > > (at a modern game pace). This is equivalent to how much
                                    > better the best Bulls
                                    > > team was to the league
                                    > > average....."
                                    > >
                                    > > I say again: yes, yes, and yes, certainly to a first
                                    approximation
                                    > and absent
                                    > > any introduced counter-argument.
                                    > >
                                    > > your 1959-60 pts/poss is .879. your 1978-79 pts/poss is 1.005.
                                    > you are saying
                                    > > that:
                                    > >
                                    > > 1 - (.879)/(1.005) = 0.126 difference in pts/poss between 59-60
                                    > and 78-79...
                                    > >
                                    > > you are then multiplying this pts/poss difference by the 78-79
                                    > game pace:
                                    > >
                                    > > 0.126 x 109.7 = 13.82 pts/g
                                    > >
                                    > > and you are then stating that because of this percent difference
                                    > that since
                                    > > these pts/poss numbers are the average for their respective
                                    > season, that an
                                    > > average team in 78-79 would beat an average team in 59-60
                                    > by almost 14
                                    > > points....
                                    > >
                                    > > but like professor morbius in the forbidden planet, you are
                                    > clueless...
                                    > >
                                    > > this calculation of yours is absolutely meaningless, because
                                    > you fail to
                                    > > realize that pts/poss, while a measure of "offensive
                                    > productivity", is at the
                                    > > same time a measure of what the defense allows per
                                    > possession. you are
                                    > > measuring simply one side of the ball, and looking only at
                                    > offense, and your
                                    > > calculation assumes that the defensive pts/poss remained the
                                    > same over that
                                    > > time...
                                    > >
                                    > > pts/poss scored is a relative number, what the offense scores
                                    > against the
                                    > > defense on average, or what the defense allows the offense to
                                    > score on
                                    > > average. it is a relative number stating the "balance" between
                                    > what the
                                    > > offense produces and what the defense gives up...
                                    > >
                                    > > in 59-60 defenses allowed only 0.879 pts/poss, as compared
                                    > to in 78-79
                                    > > defenses allowing 1.005 pts/poss. no matter how you want to
                                    > look at it, a
                                    > > defense giving up just 0.879 pts/poss is "better" than a
                                    > defense that gives
                                    > > up 1.005 pts/poss - in any game where two teams each have
                                    > the same number of
                                    > > possessions, the team giving up the least amount of pts/poss
                                    > will win. thus
                                    > > the avg team in 59-60, based on your meaningless logic,
                                    > states that 59-60 had
                                    > > the better avg defensive teams...
                                    > >
                                    > > stating that an offensive productivity of 1.005 in 78-79 is
                                    better
                                    > than 0.879
                                    > > in 59-60 is exactly the same as saying a defense allowing
                                    > 1.005 pts/poss in
                                    > > 78-79 is worse than a defense allowing just 0.879 pts/poss in
                                    > 59-60...
                                    > >
                                    > > this is exactly the same arguement you are using to say teams
                                    > of 78-79 are
                                    > > better than teams of 59-60, simply because the avg team
                                    > pts/poss is greater,
                                    > > 1.005 to 0.879. it has no basis in fact. using your formula one
                                    > can say the
                                    > > teams of 59-60 are 13.82 better on defense than teams of
                                    > 78-79, and thus if
                                    > > they played the avg 59-60 team would defeat the avg 78-79
                                    > team by that 13.82
                                    > > pts/g, actually even more because the game pace was greater
                                    > in 59-60...
                                    > >
                                    > > 0.126 x 131.2 = 16.5 pts/g
                                    > >
                                    > > thus an avg 59-60 team, because of its "better" defense, would
                                    > outscore an
                                    > > avg 78-79 team by 16.5 pts/g, normalized for the 59-60 game
                                    > pace. this
                                    > > manipulation of the numbers is worthless...
                                    > >
                                    > > a completely meaningless calculation that has no basis in
                                    > fact....
                                    > >
                                    > > bob chaikin
                                    > > bchaikin@b...
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