Re: [APBR_analysis] Dilution, balance, and Bob-bashing
- On Tue, 31 Dec 2002, Dean Oliver <deano@...> wrote:
>I hope I wasn't sounding like I was beating up on Bob. I had some problems with some ideas he had, and then I thought he got overly defensive. I have nothing against him as a person.
> I guess 'tis the season to beat up on BobC. A lot of it happened
> while I was gone, that's for sure.
>That's the crux, here. I just don't see how one can simply adjust the pace of past teams downward or decrease/increase their field goal percentages and then say that the games you sim are at all meaningful. I don't have a problem with guys who do this as a leisure activity; I'll be the first to admit that it's a lot of fun to answer, if only to yourself, whether or not the 1970 Lakers could take down the 1996 Bulls. The problem is that unlike, say, baseball, the game has changed quite a bit over the last 30 years.
> I could spend a lot of time going through and showing how
> statistically different the various eras of the NBA are. I think it
> is very clear that pace has changed most significantly, with a huge
> decrease in turnovers. That's a big change from _any_ past period to
> the present, not just '60's to today. I, for one, would not say that
> the '80's are like today either. I would say that the mid-'90's
> aren't even much like today. Hell, last year is beginning to look
> pretty different from this year with the increase in zone D being
> prominent. Statistically, you can find pace, 3pt shooting, and
> turnover rates as good indicators of how the game has changed. Non-
> statistically, the league has trended significantly toward selecting
> athletic tall players who can dribble and defend, rather than tall
> players who can just play the low post. All these 7 footers who play
> on the perimeter didn't exist even in the early '90's. Does that
> mean that Wilt couldn't have played on the perimeter? We don't know -
> - that's the point. Can you simulate something? Sure. Can you
> calibrate it or validate it? No. There is no reality check I can
> think of to do so. Calibration in my mind means having a real
> experiment -- actually playing the 1996 Bulls vs the 1972 Lakers --
> to check a simulation against. Obviously impossible. What we can do
> better is come up with reasonable statistical metrics for what any
> cross-generational simulator should have to live up to. Should they
> meet the average pace of the two generations? The average pace of
> the two teams? I guess I'd find Bob-bashing more productive if we
> can all come up with rules for what cross-generational simulators
> would do, not in specifics (Lakers should beat Bulls), but in
> For example, any games between the two shouldYes, but... were the teams of the 1970s and 80s simply faster than those of today (meaning that games should be simmed at or near their pace) or are teams nowadays better at cutting off the fast break? I don't know, and after the little study that I did (and I'll be the first to admit that it's by no means perfect) I can't even cast an opinion here. The NBA of the mid-70s appears to be of a higher talent level than at any other time, but other than that there just doesn't seem to be a lot of difference in competitive balance between now and around 1971 or '72.
> obviously result in stats where the two teams have the same number of
> possessions. That's a basketball rule.
> Or just stating the...which seems to me to be an unfair handicap, since the 2002-3 Mavs are built around running the zone a lot. If the illegal defense rules were still in place, they would likely be constituted differently, in terms of both personnel and rotation choices.
> assumptions of a cross-generational simulation would help. We assume
> that the Mavericks of 2003 are not allowed to play a zone when
> competing against the Lakers of 1987.
> Or, more likely, we assume...and I have just as much of a problem with this, as the Mavs have shown in the past that when they don't run the zone, they're not much of a defensive team.
> that the Mavericks defensive ability is independent of how they play
> defense (which is, of course, wrong but statistically practical).
>I disagree that this was a guarantee, but I agree with the point.
> Talent dilution and competitive balance
> These are two of the hardest topics around and hot topics in sports
> economics right now. We aren't going to solve them here. Standard
> deviations of various numbers across teams are a valid approach that
> gets at one way of looking at competitive balance, but is definitely
> not the whole story. (I've looked at how long it takes for teams to
> go from good to bad, bad to average, etc., as well as standard
> deviations of win-loss records, gini coefficients, how many similar
> playoff teams from one season to the next, blah blah blah.) What
> teams have the greatest chance of winning and how great those chances
> are -- that's important. I personally think that knowing the Vegas
> line on who would win the title -- at the start of the season and at
> the start of the post-season -- then who won the title is getting
> better at the underlying concern of competitive balance questions,
> which is that predetermined outcomes of sports are bad. Purely
> random outcomes may also be bad, but things that are almost
> guarantees -- the Lakers winning the title in 2001
> -- is not healthyInteresting.
> over a sustained period. That's why gambling is bad � it sets up
> situations where guys intentionally losing is possible and results
> become more predetermined. This is what some people blame the
> downfall of professional wrestling on � the WWE (formerly WWF)
> admitted that they script matches, even though most people believed
> it for a long time. Now that everyone knows it, wrestling is less
> interesting. For some of us, it was always less interesting.
> Talent dilution fits into the question of competitive balance, too,
> but I like to approach it from another angle, having tried all sorts
> of statistical things to measure it. (The one statistical measure of
> talent that works decently � not perfectly � is turnovers per
> possession, I think. I say that because it gets lower leaguewise
> from grade school to middle school to high school to college to pros
> and, being somewhat sexist here, it gets lower from female to male.
> You could use this to say that previous eras of the NBA were alsoYes, although to be fair this has been studied a lot more in baseball and many of the expansions actually didn't have a great deal of effect in league talent. There were quite a few capable players, for example, squirrelled away in farm systems and on benches of contending teams in the late 1950s who finally got a chance to play in the early 60s.
> less talented.) The fundamental problem is defining "talent". (I
> know I've said this before to this group.) Performance reflects
> talent PLUS team system, role on a team, rules, coaching, rest
> between games (there is more rest now than in the `60's, I think),
> home vs road effects and a host of (hopefully) smaller factors. We
> can measure performance and, in this discussion, have implicitly
> assumed that it only reflects talent (hence, we are measuring
> talent). But we assume wrong and, as Coach K says, "Only fools
> assume," or as the Bad News Bears said, "If you assume, it makes an
> ass out of u and me." I learned how many of life's lessons from the
> Bad News Bears? (One of those movies said that kissing makes babies
> and, boy, did that screw my teen dating life up.)
> But I get sidetracked. What statistics can be used to indicate
> talent? Using league stats has some problems, mainly due to the
> impact of rules, which change skill sets and change the balance
> between O and D, though perhaps don't change overall talent. Looking
> at how much subs played vs starters may have some role in the
> discussion. But a big hurdle is if offensive and defensive "talent"
> have been increasing or decreasing at equal rates, the performance
> stats won't show anything. Does anyone have any idea on how to deal
> with that?
> Someone pointed out that talent almost assuredly gets diluted in
> expansion years. This is true and is a minimum test of any statistic
> we use for assessing average level of talent.
> Many statistics shouldIt wasn't even looking at FG%, per se. It was looking at the differences between FG% between individual players. One would assume that as the overall talent level of a basketball league increases, players who shoot really, really poorly would shoot less and in situations better suited to their limited abilities (raising their FG%), and conversely the really really great players would be increasingly less better than the league average. This is an imperfect stat, since the NBA obviously doesn't determine who will play and shoot based solely on their FG% (or EfFG% later on). I was hoping that that effect would cancel itself out from year to year; unfortunately, it looked like there was still a good deal of noise.
> show this, however. I believe MikeG had some stat a long time ago
> showing how much net gain in minutes played per player there was,
> which was a weird stat (one I'm not sure about), but certainly shows
> expansion years and possibly other things. I think
> turnovers/possession would show expansion years, too. Would FG% do
> that? It's a purely offensive stat. Does this mean that "talent" is
> primarily an offensive thing? What other statistics can we use?
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> I particularly enjoyed Rosen's article on the Sonics where hewatched
> one game (one of the worst of the year, for what it's worth) andPut me firmly in the "pompous windbag" camp. The best thing about the
> acted like he knew something about the team. Apparently, Desmond
> Mason can't make a jumper because he had one bad night.
Mason comment, for instance, was that Rosen said the reason Mason
can't make a jumper was his "low release point", which was hilarious
on several levels:
1) Apparently he's never watched Steve Kerr. Or Andrew Toney. Or
Bryce Drew. Or about a hundred other guys who shoot from under their
chin but make everything.
2) Mason's release point isn't low, especially given that he's about
20 feet off the ground when he shoots it.
3) Mason's problem isn't the release point, it's the lack of arc on