There are other reviews arriving. In addition to Dan's, you can reach one by Roland thru his site, and I see David Lewin has a review of it up there now too, and there is a note saying Kevin will have one there soon.
Posted: Tue Aug 01, 2006 6:56 pm Post subject: replacement level FG% and shot creation value
What is the replacement level / no real shot creation value added FG%?
If you simply take a typical contested 2 point shot? Ed Peterson's extreme charting provides one estimate at between 35-40%. http://www.82games.com/saccon.htm
Team by team data for shots in crunch last 3 second of shotclock also seems to center roughly around 40% (I didnt actually calculate the average). http://www.82games.com/clockx.htm
Perhaps players should get credit in some fashion (as a separate stat or in larger formulas) for varying level of shot creation value if they get a shot with expected FG% better than this new baseline level of a shot instead of using the perhaps too high standard of 50% or even league average (which have shot creation value in them)? Of course actual success / failure would still be scored same as value of basket (or scoring play) / no basket.
It is another way to view things, maybe too lenient but I wanted to try to find a way to show credit for shot creation.
(Average actual FG% of players by position within a certain distance of replacement level on overall player quality might be worth looking at too as an additional reference, but because it can be affected by shot creating impact of others, or reflect low man of the totum pole, and against subs and garbage time I'd prefer to stick the approaches mentioned above.)
Last edited by Mark on Tue Aug 01, 2006 9:27 pm; edited 1 time in total
Posted: Tue Aug 01, 2006 9:25 pm Post subject: Search for how best to distribute the shots
Has anyone created or seen some sort of game theory model where for a specif team matchup and each the five positions on the floor you compared own TS% and TS% allowed and established some help defense rules that would dampen FG% where applied at some cost elsewhere and determined (by simulation?) the optimal shot distribution?
Bob C., does your simulation need to take a shot distribution or can it find the optimal one too? Quickly or would be require a really long process? Need to apply much more computing horsepower?
Dan R. would it be possible to work with the massive dataset you used for adjusted +/- to chronicle actual shot distribution game to game by position. role, player quality with the counterpart offense /defense FG% matchup data for each play summed up and see at least at a surface level how consistent actual shot distribution was compared to what a strategic analysis might suggest was optimal? And if there were any common themes in which overall game shot patterns succeeded above expected or at some simplified level (backcourt/frontcourt, inside/outside/3, star/role player) which play by play sequences succeeded above expected?
Last edited by Mark on Wed Aug 02, 2006 12:56 pm; edited 1 time in total
Joined: 03 Jan 2005 Posts: 413 Location: Greensboro, North Carolina
Posted: Tue Aug 01, 2006 11:21 pm Post subject:
Mark, game log databases can be used in a lot of ways, and what you suggest may be possible.
Back to a question above, I was able to regress a player's offensive adjusted plus/minus rating onto their true shot attempts per 40 minutes. I was able to hold constant a player's true shooting percentage, how many "extra" points they scored relative to if they had shot 50 percent, their turnover rate, and their rebound rate.
The things I am holding constant should account for practically everything that the given player contributes to offensive efficiency directly through their shooting, turnovers, and rebounding. What the coefficient on true shot attempts per 40 minutes tells us is how much scorers help offensive efficiency of their teammates. And the upshot is that increasing true shot attempts by 4 (one standard deviation) increases offensive efficiency by about 1 point per 40 minutes.
Take away Allen Iverson's true shot attempts and replace him with a player who shoots an average amount of shots (but is otherwise the same) and we are looking at offensive efficiency dropping by about 3 points per 40 minutes.
Moreover, only about 1/3 of this effect is due to teammates' shooting efficiency increasing. The bulk of the effect comes from teams with scorers turning the ball over less.
These effects are highly statistically significant (t-stat=9.12), so this is strong evidence that scorers do, on average, positively affect their teammates. The surprise is that the effect is mostly through teammates commiting fewer turnovers rather than shooting better.
Awesome work Dan. I never really thought about it in terms of teamattes not commiting turnovers, but intuitively I always felt that even Iverson is helping his team if his offensive efficiency is below his teams average by a decent amount. His high Usage does indeed help the offense. Only question is would his efficiency rise a lot with less Usage and more offensive help? AKA what would Iverson's Dean Oliver skill curve be like with a good quality offensive supporting cast?
It seems on the Wages board you overvalued the role players (or maybe it was Dave Berri) IMO. Does this new finding of yours give you a little more respect for Iverson, or do you still feel the role players were much more important than given credit for? What is your subjective opinion based on these objective stats about that 2001 Philly team? Personally I felt the defense (Ratliff then Dikemebe helped a lot -- along with having excellent defensive role players). But without Iverson's high Usage and high quality play, those role players might have been able to play such a high level defense, nor be as offensively efficient as they were.
Joined: 03 Jan 2005 Posts: 413 Location: Greensboro, North Carolina
Posted: Wed Aug 02, 2006 7:29 am Post subject:
I still do not find Iverson to be particularly effective - he rates a little above average. His relatively poor shooting does hurt and he is a pretty poor defender. The evidence seems to suggest that with all of the energy he expends on offense, he takes a lot of plays off on defense. So the positive effects he has on reducing the team turnovers rate (he is one of the best in the league at this) are offset by his defense.
So your saying Iverson in 2001 was just a good player, or above average but not by much?
Could it be a coincidence that his defense might be perceived as bad, because he has to play so hard on offense? Doesn't his offense allow those role players to have meaningful roles to play to begin with?
Subjectively, don't you think that he would fit in on a team like the Spurs? Who have excellent defense and good offensive players (Duncan etc...) and could make his numbers and thus his +/- stats more impressive? You mentioned your +/- aren't neccesarily conclusive unless they span over multiple years -- but even then team dynamics and player health/age can change dramatically. Some players could have drastically different +/- yet still produce similiar stats. Doesn't mean they aren't of a similiar calibur player.
I guess I just don't see how the 01 Sixers can win 56 games with a bunch of average role players. What teams in the past have ever done that?
Joined: 03 Jan 2005 Posts: 413 Location: Greensboro, North Carolina
Posted: Wed Aug 02, 2006 9:03 am Post subject:
Nikos wrote:
So your saying Iverson in 2001 was just a good player, or above average but not by much?
Could it be a coincidence that his defense might be perceived as bad, because he has to play so hard on offense? Doesn't his offense allow those role players to have meaningful roles to play to begin with?
Subjectively, don't you think that he would fit in on a team like the Spurs? Who have excellent defense and good offensive players (Duncan etc...) and could make his numbers and thus his +/- stats more impressive? You mentioned your +/- aren't neccesarily conclusive unless they span over multiple years -- but even then team dynamics and player health/age can change dramatically. Some players could have drastically different +/- yet still produce similiar stats. Doesn't mean they aren't of a similiar calibur player.
I guess I just don't see how the 01 Sixers can win 56 games with a bunch of average role players. What teams in the past have ever done that?
I suspect that Iverson was a little better in 2000-01; his stats suggest that his adjusted plus/minus ratings (I don't have data that far back) would have been better that year. And on the Wages of Wins blog, I made a case for how he could be an MVP in a situation like what transpired in 2000-01. I am not quite sure that he was that good, but I do believe that he provides a team a fairly unique opportunity to load up on really good role players, which is what Philly did in 2000-01.
I suspect that Iverson was a little better in 2000-01; his stats suggest that his adjusted plus/minus ratings (I don't have data that far back) would have been better that year. And on the Wages of Wins blog, I made a case for how he could be an MVP in a situation like what transpired in 2000-01. I am not quite sure that he was that good, but I do believe that he provides a team a fairly unique opportunity to load up on really good role players, which is what Philly did in 2000-01.
Which of his stats suggest that his adj +/- in 2001 would have been better? Is it that he rebounded slightly better and got more steals?
Because, from a PER-perspective, his last season was his career-best. He had a much higher assist-rate, his turnover-rate was about the same, and his TS% was a career high.
Joined: 03 Jan 2005 Posts: 413 Location: Greensboro, North Carolina
Posted: Wed Aug 02, 2006 11:02 am Post subject:
deepak_e wrote:
Which of his stats suggest that his adj +/- in 2001 would have been better? Is it that he rebounded slightly better and got more steals?
Because, from a PER-perspective, his last season was his career-best. He had a much higher assist-rate, his turnover-rate was about the same, and his TS% was a career high.
The good role players around him made him more valuable that season. They made the other team less efficient on offense and that allowed Iverson's efficiency relative to the opposition to rise. In essence, what happened was the Philly role players changed the game into where Iverson's relatively inefficient shots were good shots rather than mediocre shots. This is another case where context matters.
These effects are highly statistically significant (t-stat=9.12), so this is strong evidence that scorers do, on average, positively affect their teammates. The surprise is that the effect is mostly through teammates commiting fewer turnovers rather than shooting better.
However, if I had to make an argument supporting the idea that great players make their teammates better, these would just about be the first two effects I would look for, as follows:
1) Decrease in turnovers - results from the primary scorer being able to or asked to create his own shot, thus lessening the need for other players to handle the ball.
2) Increase in shooting efficiency from the field - results, obviously, from the defense being concentrated on the primary scorer, giving the role players easier, more open shots.
Joined: 13 Jan 2005 Posts: 168 Location: Iowa City
Posted: Wed Aug 02, 2006 11:12 am Post subject:
Dan Rosenbaum wrote:
This is really interesting. Both Win Score and Wins Produced are both pretty terrible without position adjustments, but with the position adjustment they are not bad. It suggests that a lot of other methods have overvalued shot creation.
Dan, would you mind expanding on this last sentence here?
Joined: 03 Jan 2005 Posts: 413 Location: Greensboro, North Carolina
Posted: Wed Aug 02, 2006 11:27 am Post subject:
Ben wrote:
Dan Rosenbaum wrote:
This is really interesting. Both Win Score and Wins Produced are both pretty terrible without position adjustments, but with the position adjustment they are not bad. It suggests that a lot of other methods have overvalued shot creation.
Dan, would you mind expanding on this last sentence here?
Without getting into specifics, I am treading a fine line here in that I am arguing that the value of shot creation is greater than what Wages of Wins assumes (i.e. zero), but less than what is implicitly assumed by metrics such as NBA Efficiency and PER. Hopefully that is helpful.
Joined: 13 Jan 2005 Posts: 168 Location: Iowa City
Posted: Wed Aug 02, 2006 11:42 am Post subject:
Dan Rosenbaum wrote:
Ben wrote:
Dan Rosenbaum wrote:
This is really interesting. Both Win Score and Wins Produced are both pretty terrible without position adjustments, but with the position adjustment they are not bad. It suggests that a lot of other methods have overvalued shot creation.
Dan, would you mind expanding on this last sentence here?
Without getting into specifics, I am treading a fine line here in that I am arguing that the value of shot creation is greater than what Wages of Wins assumes (i.e. zero), but less than what is implicitly assumed by metrics such as NBA Efficiency and PER. Hopefully that is helpful.
Yes, thanks. I guess you would put it closer to where Orating,Drating, Win Shares does? In between that and PER?
[edit to add questions.]
Last edited by Ben on Wed Aug 02, 2006 11:44 am; edited 1 time in total
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