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effeciency per possession versus minutes played, FG%, etc

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  • bchaikin@aol.com
    I think it is just simply a matter of seeing to what extent fg% and to/possessions change in between 2 seasons of the same player. Take some examples of
    Message 1 of 5 , Oct 8, 2002
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      I think it is just simply a matter of seeing to what extent fg% and
      to/possessions change in between 2 seasons of the same player. Take
      some examples of players who shifted from go-to-guys to supplementary
      guys (or vice versa):

      I know it is a small smaple but it does not look like, as Dean said,
      there is much fg% variation, but turnovers are always up. (i did not
      look at how many extra shots or free throws they generate in each
      situation).

      again "efficiency" is hard to define, buts let look at the examples you gave, rather than try to paint this idea of efficiency with a broad brush. i added some more stats to try to make clear each example:

                                                    eff     Prod  Poss                                            reb    Pts
      Hawkins mpg ppg  fg% To/min FG%  Rat   Fact  %sht %3sht %fld %to %pass /48   Poss
      90-91      38.9 22.1 47.2 .068   .515   .471   1.07    38      8       14     6     42     4.8  .533
      95-96      34.4 15.6 47.3 .058   .554   .387   0.89    37     15       10    6     47     5.0   .507

      here for hersey hawkins the turnovers are the same, 6 turnovers per 100 ball possessions, so that's not the difference. he did get fouled quite alot more (4%) in 90-91, in fact his FTM in 90-91 was twice that in 95-96. but he shot better in 95-96, so its not shooting (took twice as many 3pters in 95-96 per ball possession than in 90-91). the biggest difference that i can see is he handled the ball about 20% more often per minute in 90-91, and add that to his 5 more min/g is the reason he played better. why did he handle the ball more earlier? in 90-91 he was on PHI and 95-96 he was one SEA. in philly the only other offensive threat was barkley, the other major players were rick mahorn, ron anderson, armon gilliam, and manute bol, all low touches/min players (rickey green was the PG). in SEA gary payton, shawn kemp, and detlef schrempf all could score and handle the ball, thus hawkins' wasn't a main offensive weapon and his touches/min were down...

                                                    eff     Prod  Poss                                            reb    Pts
      Barkley  mpg ppg  fg% To/min FG%  Rat   Fact  %sht %3sht %fld %to %pass /48   Poss
      95-96      37.1 23.2 50.0 .082   .521   .672   1.25    35     5        15     7     43    15.0  .502
      96-97      37.9 19.2 48.4 .075   .526   .640   1.30    27     8        14     6     53    17.1  .389

      for charles barkley the first season was in PHO, the second in HOU. his possession factor (touches/min) are about the same both seasons, yet you can see he made a conscience effort to pass more and shoot less in 96-97. why? well he went from a team in PHO where he was the leading scorer and rebounder, the main offensive weapon on the team, and the 2nd best scorer was the PG (kevin johnson). michael finley played almost 40 min/g but scored only 15 pts/g, wesley person just under 13 pts/g in 32 min/g. the C spot was handled by a number of, ...err,... stiffs...

      but barkley went to houston the next year to play with two future hall of famers, olajuwon and drexler, so you would expext his poss fact to decrease somewhat. but instead he made a conscience effort to pass more and shoot less, and thus maintained his touches/min (even increase it slightly) by passing more to these better teammates (better than the year before). plus he rebounded better. his PTS/POSS were down obviously as he was passing more, but he shot just as well, got fouled just as often, and turned the ball over about the same...

                                                    eff     Prod  Poss                                            reb    Pts
      Pippen   mpg ppg  fg% To/min FG%  Rat   Fact  %sht %3sht %fld %to %pass /48   Poss
      92-93      38.6 18.6 47.3 .079   .482   .513   1.36    31     2         7      6     56     9.5   .354
      93-94      38.3 22.0 49.1 .084   .515   .594   1.38    34     5         9      6     51    10.9   .417

      biggest difference was jordan was playing baseball in 93-94 after scoring 32.6 pts/g in 92-93. i like many others was expecting pippen to improve much more than he did, but lets see what did happen...

      pippen played the same amount, handled the ball just as often. with jordan gone, who else was handling the ball? horace grant handled the ball about 15% more often, and toni kukoc played 24 min/g and was the team's 2nd highest touches/min ballhandler behind pippen. bj armstrong was about the same, and believe it or not pete myers handled the ball about once a minute, passing it about 60% of the time, and steve kerr played 25 min/g with 0.85 touches/min....

      pippen shot better, and shot more often per 100 ball possessions, but only 3% more, and got fouled a little more. he still passed the ball off half the time. he was 1st team all-D in 91-92, 92-93, and 93-94, and was only 3rd team all-league in 92-93 but 1st team all-league in 93-94, so he impressed a number of people to be one of the top 5 in the league. the bulls were 57-25 in 92-93 yet only 2 games worse in 93-94 at 55-27 without jordan. how is this possible? well in 92-93 they outscored their opponents by 6.3 pts/g but just 3.1 pts/g in 93-95, so their W-L record of 55-27 was probably a few to a number of games better than their stats would indicate...

      Larry Johnson                          eff     Prod  Poss                                            reb    Pts
                    mpg ppg  fg% To/min FG%  Rat   Fact  %sht %3sht %fld %to %pass /48   Poss
      95-96      40.4 20.5 47.6 .056   .503   .508   1.17    32     5       13      5     50    10.0   .435
      96-97      34.4 12.8 51.2 .052   .535   .312   0.80    35     5        11     6     48      7.2   .466

      95-96 in CHA, 96-97 in NYK. went from a team that had two major offensive threats (he and glen rice, centers were matt geiger, robert parish, and zidek, kenny anderson the PG), to the knicks where ewing was clearly the 1st offensive option. plus he switched from being a power forward to a small forward. his PTS/POSS are about the same, his shooting even better in 96-97. the biggest difference i can see (other than rebounding) is he handled the ball over 30% less in NY (that's a huge drop) as he was on the floor with oakley, starks, and allan houston. in CHA it was him and rice with dell curry and very low touches/min centers matt geiger and parish...

                                                    eff     Prod  Poss                                            reb    Pts
      Mason    mpg ppg  fg% To/min FG%  Rat   Fact  %sht %3sht %fld %to %pass /48   Poss
      94-95      32.4   9.9 56.6 .049   .566   .417   0.85    24    0        12      6     58    12.5    .359
      95-96      42.2 14.6 56.3 .061   .563   .435   0.96    24    0         11     6     59     10.6   .359

      both years in NYK. only major difference here is the large increase in playing time the 2nd season. player attributes (%sht, %fld, %to, %pass) almost identical, rebounding less. charles smith (the 6'10" PF/SF) missed significant time with injuries in 95-96, anthony bonner gone (another bulky front court guy), thus mason's increase in min. his PTS/POSS are the same, his PROD RAT (tendex) slightly better. his turnovers are about the same, his 10% increase in possession factor due to starks, derek harper, and ewing all handling the ball slightly less than in 94-95. team was 8 games worse in 95-86 (47 wins versus 55 in 94-95)...
      so each case is slightly different, with a large change in touches/min being significant in just two of the five cases (hawkins and grandmama)....

      bob chaikin
      bchaikin@...

    • Mike G
      Bob, good job on the clarification of methods. I see line 1 and line 2 of the statistics headings are misaligned, and some of the categories are actually
      Message 2 of 5 , Oct 9, 2002
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        Bob, good job on the clarification of methods. I see line 1 and line
        2 of the statistics headings are misaligned, and some of the
        categories are actually `effective FG%', `production
        rating', `possession factor', `rebounds/48 min',
        and `points/possession'. Correct me if I didn't get these right.

        Then, I see %shot + %fouled + %turnover + % pass = 100 in every case.

        The Possession Factor then must be guesstimated to create a total
        touches out of the possessions used, and determines those breakdowns
        listed above.


        >i added some more stats to try to make clear each example:

        eff Prod
        Poss reb Pts
        Hawkins mpg ppg fg% To/min FG% Rat Fact %sht %3sht %fld %to %
        pass /48 Poss
        90-91 38.9 22.1 47.2 .068 .515 .471 1.07 38
        8 14 6 42 4.8 .533
        95-96 34.4 15.6 47.3 .058 .554 .387 0.89 37
        15 10 6 47 5.0 .507

        >here for hersey hawkins the turnovers are the same, 6 turnovers per
        >100 ball possessions, so that's not the difference. he did get
        >fouled quite alot more (4%) in 90-91, in fact his FTM in 90-91 was
        >twice that in 95-96. but he shot better in 95-96, so its not
        >shooting (took twice as many 3pters in 95-96 per ball possession
        >than in 90-91). the biggest difference that i can see is he handled
        >the ball about 20% more often per minute in 90-91, and add that to
        >his 5 more min/g is the reason he played better

        Greater FG %, more 3-point attempts, fewer FT attempts: what does it
        all add up to?

        .554 is a lot higher than .515, and 14% is a lot more than 10%.
        However, Hawkins' overall shooting was .579 in '91, and .591 in '96,
        only a small difference. In Charlotte, 1995, he had his career high
        of .611


        eff Prod
        >Poss reb Pts
        >Barkley mpg ppg fg% To/min FG% Rat Fact %sht %3sht %fld %to %
        pass /48 Poss
        95-96 37.1 23.2 50.0 .082 .521 .672 1.25 35
        5 15 7 43 15.0 .502
        96-97 37.9 19.2 48.4 .075 .526 .640 1.30 27
        8 14 6 53 17.1 .389

        >…. he shot just as well, got fouled just as often, and turned the
        >ball over about the same...

        Yep. Barkley's overall shooting was .571 in '96 and .566 in '97, and
        dropped steadily thereafter. His 1997 rebounding rate was the best
        of his career, outside of 1987.


        eff Prod
        >Poss reb Pts
        Pippen mpg ppg fg% To/min FG% Rat Fact %sht %3sht %fld %to %
        pass /48 Poss
        92-93 38.6 18.6 47.3 .079 .482 .513 1.36 31
        2 7 6 56 9.5 .354
        93-94 38.3 22.0 49.1 .084 .515 .594 1.38 34
        5 9 6 51 10.9 .417

        >… i like many others was expecting pippen to improve much more than
        >he did

        '93 was a bad year for Pippen. In '92 he had approached
        superstardom, and struggled the year after. His shooting % was the
        lowest of any year between his rookie season and last season.

        ... the bulls were 57-25 in 92-93 yet only 2 games worse in 93-94 at
        55-27 without jordan. how is this possible? well in 92-93 they
        outscored their opponents by 6.3 pts/g but just 3.1 pts/g in 93-95,
        so their W-L record of 55-27 was probably a few to a number of games
        better than their stats would indicate...

        This is pretty radical. Does anyone know what team ppg differential
        typically produces in terms of W-L record? My guess is 6.3 ppg and
        57-25 is closer to normal, like Bob says, than 3.1 ppg and 55-27 is.


        >Larry Johnson eff Prod
        >Poss reb Pts
        mpg ppg fg% To/min FG% Rat Fact %sht %3sht %fld %
        to %pass /48 Poss
        95-96 40.4 20.5 47.6 .056 .503 .508 1.17 32 5
        13 5 50 10.0 .435
        96-97 34.4 12.8 51.2 .052 .535 .312 0.80 35
        5 11 6 48 7.2 .466

        >…, his shooting even better in 96-97. the biggest difference i can
        >see (other than rebounding) is he handled the ball over 30% less in
        >NY …

        Assists were also way down in the NY system. This surprised me,
        since he replaced Mason, another passing forward.

        Total shooting pct went from .551 to .560.


        Mike G
      • Dean Oliver
        A key philosophy I ve worked on is that players can only stay the same or get less efficient as they take on a greater load of the offense, given their
        Message 3 of 5 , Oct 9, 2002
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          A key philosophy I've worked on is that players can only stay the
          same or get less efficient as they take on a greater load of the
          offense, given their teammates. Basically, they have to take worse
          shots or make more mistakes. This concept has to be true to some
          degree, otherwise the Bulls should have ALWAYS given the ball to
          Jordan, every single time. Players have to become less efficient as
          they take more possessions or else you'd have players like Steve
          Kerr, shooting 50% from the 3pt line, who should always shoot the
          ball.

          There are players who, with a basic look at their numbers, don't
          support this. Iverson is one. His efficiency goes up with more
          possessions. Why? Because there are nights when a team tries to
          cover him 1 on 1 and he gets hot, so he goes all night killing the
          horrible defense. But such a look at offensive rating (points
          produced per 100 possessions vs possessions used) is mixing cause and
          effect. If a team were double teaming him and he kept trying to
          score, his efficiency would go down. Fundamentally, it is very hard
          to sort out cause and effect in looking at efficiency vs the load
          that players take on.

          The examples cited below are reasonable, but also ignore the distinct
          role players like Ron Harper and Rick Fox. Hersey Hawkins is
          probably a fair example of a role player whose role changed, though.

          And, oh yeah, I always define efficiency in terms of either a floor %
          (scoring possessions per possession) or points produced per 100
          possessions. Formulas for these on my website.

          I'll get back to this.... Meeting now...

          --- In APBR_analysis@y..., "Mike G" <msg_53@h...> wrote:
          > Bob, good job on the clarification of methods. I see line 1 and
          line
          > 2 of the statistics headings are misaligned, and some of the
          > categories are actually `effective FG%', `production
          > rating', `possession factor', `rebounds/48 min',
          > and `points/possession'. Correct me if I didn't get these right.
          >
          > Then, I see %shot + %fouled + %turnover + % pass = 100 in every
          case.
          >
          > The Possession Factor then must be guesstimated to create a total
          > touches out of the possessions used, and determines those
          breakdowns
          > listed above.
          >
          >
          > >i added some more stats to try to make clear each example:
          >
          > eff Prod
          > Poss reb Pts
          > Hawkins mpg ppg fg% To/min FG% Rat Fact %sht %3sht %fld %to %
          > pass /48 Poss
          > 90-91 38.9 22.1 47.2 .068 .515 .471 1.07 38
          > 8 14 6 42 4.8 .533
          > 95-96 34.4 15.6 47.3 .058 .554 .387 0.89 37
          > 15 10 6 47 5.0 .507
          >
          > >here for hersey hawkins the turnovers are the same, 6 turnovers
          per
          > >100 ball possessions, so that's not the difference. he did get
          > >fouled quite alot more (4%) in 90-91, in fact his FTM in 90-91 was
          > >twice that in 95-96. but he shot better in 95-96, so its not
          > >shooting (took twice as many 3pters in 95-96 per ball possession
          > >than in 90-91). the biggest difference that i can see is he
          handled
          > >the ball about 20% more often per minute in 90-91, and add that to
          > >his 5 more min/g is the reason he played better
          >
          > Greater FG %, more 3-point attempts, fewer FT attempts: what does
          it
          > all add up to?
          >
          > .554 is a lot higher than .515, and 14% is a lot more than 10%.
          > However, Hawkins' overall shooting was .579 in '91, and .591
          in '96,
          > only a small difference. In Charlotte, 1995, he had his career
          high
          > of .611
          >
          >
          > eff Prod
          > >Poss reb Pts
          > >Barkley mpg ppg fg% To/min FG% Rat Fact %sht %3sht %fld %to %
          > pass /48 Poss
          > 95-96 37.1 23.2 50.0 .082 .521 .672 1.25 35
          > 5 15 7 43 15.0 .502
          > 96-97 37.9 19.2 48.4 .075 .526 .640 1.30 27
          > 8 14 6 53 17.1 .389
          >
          > >…. he shot just as well, got fouled just as often, and turned the
          > >ball over about the same...
          >
          > Yep. Barkley's overall shooting was .571 in '96 and .566 in '97,
          and
          > dropped steadily thereafter. His 1997 rebounding rate was the best
          > of his career, outside of 1987.
          >
          >
          > eff Prod
          > >Poss reb Pts
          > Pippen mpg ppg fg% To/min FG% Rat Fact %sht %3sht %fld %to %
          > pass /48 Poss
          > 92-93 38.6 18.6 47.3 .079 .482 .513 1.36 31
          > 2 7 6 56 9.5 .354
          > 93-94 38.3 22.0 49.1 .084 .515 .594 1.38 34
          > 5 9 6 51 10.9 .417
          >
          > >… i like many others was expecting pippen to improve much more
          than
          > >he did
          >
          > '93 was a bad year for Pippen. In '92 he had approached
          > superstardom, and struggled the year after. His shooting % was the
          > lowest of any year between his rookie season and last season.
          >
          > ... the bulls were 57-25 in 92-93 yet only 2 games worse in 93-94
          at
          > 55-27 without jordan. how is this possible? well in 92-93 they
          > outscored their opponents by 6.3 pts/g but just 3.1 pts/g in 93-95,
          > so their W-L record of 55-27 was probably a few to a number of
          games
          > better than their stats would indicate...
          >
          > This is pretty radical. Does anyone know what team ppg
          differential
          > typically produces in terms of W-L record? My guess is 6.3 ppg and
          > 57-25 is closer to normal, like Bob says, than 3.1 ppg and 55-27 is.
          >
          >
          > >Larry Johnson eff Prod
          > >Poss reb Pts
          > mpg ppg fg% To/min FG% Rat Fact %sht %3sht %fld %
          > to %pass /48 Poss
          > 95-96 40.4 20.5 47.6 .056 .503 .508 1.17 32
          5
          > 13 5 50 10.0 .435
          > 96-97 34.4 12.8 51.2 .052 .535 .312 0.80 35
          > 5 11 6 48 7.2 .466
          >
          > >…, his shooting even better in 96-97. the biggest difference i can
          > >see (other than rebounding) is he handled the ball over 30% less
          in
          > >NY …
          >
          > Assists were also way down in the NY system. This surprised me,
          > since he replaced Mason, another passing forward.
          >
          > Total shooting pct went from .551 to .560.
          >
          >
          > Mike G
        • John Hollinger
          ... at ... games ... differential ... The 3.1 and 55 wins is the fluke, should be more like 50. A good rule of thumb is to multiply the point differential by
          Message 4 of 5 , Oct 10, 2002
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            > ... the bulls were 57-25 in 92-93 yet only 2 games worse in 93-94
            at
            > 55-27 without jordan. how is this possible? well in 92-93 they
            > outscored their opponents by 6.3 pts/g but just 3.1 pts/g in 93-95,
            > so their W-L record of 55-27 was probably a few to a number of
            games
            > better than their stats would indicate...
            >
            > This is pretty radical. Does anyone know what team ppg
            differential
            > typically produces in terms of W-L record? My guess is 6.3 ppg and
            > 57-25 is closer to normal, like Bob says, than 3.1 ppg and 55-27 is.
            >

            The 3.1 and 55 wins is the fluke, should be more like 50. A good rule
            of thumb is to multiply the point differential by about 2.8, then add
            41. This doesn't work at the extremes (a +15.0 team would have 83
            wins and negative one losses), but as a practical matter it's very
            effective.
          • Michael K. Tamada
            ... Yup, this is what separates econometrics from most other branches of statistics: heavy reliance on theory or assumptions, to determine the resulting
            Message 5 of 5 , Oct 15, 2002
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              On Wed, 9 Oct 2002, Dean Oliver wrote:

              >
              > A key philosophy I've worked on is that players can only stay the
              > same or get less efficient as they take on a greater load of the
              > offense, given their teammates. Basically, they have to take worse

              Yup, this is what separates econometrics from most other branches of
              statistics: heavy reliance on theory or assumptions, to determine the
              resulting statistical procedures or interpretations.

              > shots or make more mistakes. This concept has to be true to some
              > degree, otherwise the Bulls should have ALWAYS given the ball to
              > Jordan, every single time. Players have to become less efficient as
              > they take more possessions or else you'd have players like Steve
              > Kerr, shooting 50% from the 3pt line, who should always shoot the
              > ball.

              Yes, two good concepts being used here: proof by contradiction. And the
              principle of diminishing marginal returns. They HAVE to diminish.

              Another example would be Artis Gilmore late in his career, when he was
              shooting something like 65% from the field. Why didn't he just shoot the
              ball 40 times per game? For the obvious reason that his FG% (and
              efficiency) would've gone way down.

              > There are players who, with a basic look at their numbers, don't
              > support this. Iverson is one. His efficiency goes up with more
              > possessions. Why? Because there are nights when a team tries to
              > cover him 1 on 1 and he gets hot, so he goes all night killing the
              > horrible defense. But such a look at offensive rating (points
              > produced per 100 possessions vs possessions used) is mixing cause and
              > effect. If a team were double teaming him and he kept trying to
              > score, his efficiency would go down. Fundamentally, it is very hard
              > to sort out cause and effect in looking at efficiency vs the load
              > that players take on.

              This is a good example, but is only one of the complications. It's also
              an example of how we rely upon our theory or assumptions: in this case
              the assumption that, all else being equal, an increase in possessions by
              a player must result in a decrease in his efficiency. If we observe
              some player's stats going in the opposite direction, such as Iverson, we
              resort to explanations such as DeanO's.

              A good procedure, but only as long as the theory or assumptions are good.
              In this case, the assumption of diminishing marginal returns is a good
              one.

              But there are yet other complications which make estimating the
              possession/efficency tradeoff difficult. In addition to the defensive
              context, there's the teammate context: what sort of teammates does the
              player have, how good are they, do their skills complement each other
              (Shaq & Kobe) or compete with each other (Bellamy & Willis Reed, Wilt &
              Thurmond -- there was no point in having both of those players on one
              team, the team was better off trading one of them away). During a season,
              most of the teammates remain constant at least so we can try to use
              individual game data to explore the relationship between possessions and
              efficiency.

              But then there's yet another complication, especially when we're looking
              at a player's career across time: the quality of the player almost
              certainly varies. Most players improve, plateau, and then decline. So
              their possession/efficiency tradeoff is going to be varying over time.

              It's like trying to estimate the relationship between how fast you drive
              and what kind of gas mileage you get: but some days your car is a Ford
              Excursion and some days it's a Ford Fiesta or whatever they call those
              little cars. Fortunately career swings aren't completely random, there's
              some regularity and stability to them.


              --MKT
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