APBRmetrics

Flint · Joined: 25 Mar 2007 Posts: 112

Ok. What percentage of a players contribution does it ostensibly capture?

asimpkins · Joined: 30 Apr 2006 Posts: 244 Location: Pleasanton, CA

A good question, and a complicated one.

I couldn't give a definitive answer, but for the sake of discussion I would estimate that the box score doesn't represent somewhere between 25%-50% of the important things that happen in the game.

And I know you're more comfortable attacking PER than considering flaws in WoW, but PER is based on the exact same limited information as WoW is. Whatever shortcomings the box score represents, they apply to WoW just as much.

Neither is a measure of a full contribution to winning a game. I don't think even Berri would argue with that.

Harold Almonte · Joined: 04 Aug 2006 Posts: 616

And the defense rating he created to make up for the lack of information in boxscore, is so fairly distributed that doesn't give more valid information than the unadjusted +/- that some ratings use to compound with PER, or than PER counterpart.

Flint · Joined: 25 Mar 2007 Posts: 112

Mike G wrote in the player losses thread that his intention was to create:

"a win-based player metric that stood up to translation from one team environment to another."

Isn't that the goal here? Isn't that what an advanced player metric should be?

And given what you have said about PER, can it really even be considered an advanced player metric in that sense? It seems like a no to me.

Maybe that shouldn't be the goal, maybe it's an impossible goal, I don't know. But I do have trouble with the fact that PER is popularly perceived to be an accurate guide to a player's full value, when in fact, as you say, it isn't even actually intended to be that.

Harold Almonte · Joined: 04 Aug 2006 Posts: 616

I think nobody thinks is a full accurate guide, just that the logic is better and more acceptable, and doesn't try to overdo statistical methods like to do a team win regression to a stat whose action is shared in the game with another one that is not boxscored, that's is to overrate the stat.

asimpkins · Joined: 30 Apr 2006 Posts: 244 Location: Pleasanton, CA

Flint. I've stated it twice already, and you don't seem to have absorbed it. Maybe you are psychologically blocking out words that offer any criticism to WoW? But I'll try one last time.

WoW is based on box scores, just as PER is. Thus, WoW offers an incomplete picture of player contributions towards wins, just as PER does. In this sense, PER and WoW are the same. WoW is as much an advanced metric as PER is. Any criticism you level at PER on this matter applies equally to WoW. It is a feature of any box score only metric.

Harold Almonte · Joined: 04 Aug 2006 Posts: 616

Do you think that a proffessional statician who knows and applies the odds for a block to be defensive rebounded (applies to block only of course), can do the blind to the same odds between an OReb and a DReb. after a FGMissed?

Flint · Joined: 25 Mar 2007 Posts: 112

Ok. Clearly this is a discussion that has happened before. I got it. What you are saying is that no method based on tracked box score stats can capture a player's full value. Only plus/minus data can do so, and only when proprietary techniques are applied.

That's fair enough, duly noted. I disagree of course.

asimpkins · Joined: 30 Apr 2006 Posts: 244 Location: Pleasanton, CA

I haven't said anything about plus/minus or proprietary techniques??

I can only take this as another sign that you aren't actually having a conversation with me... you're just here to preach the Wages of Win?

Flint · Joined: 25 Mar 2007 Posts: 112

You believe you cannot paint a complete picture of a player's value using box score stats tracked for teams and individuals, correct?

Guy · Joined: 02 May 2007 Posts: 128

asimpkins · Joined: 30 Apr 2006 Posts: 244 Location: Pleasanton, CA

Guy · Joined: 02 May 2007 Posts: 128

Flint: Jason flies solo over at WOW today, with a post on the consequences of Houston losing Olajuwon for a chunk of the 1990-91 season. I think it may help clarify the discussion/debate over what Berri calls "diminishing returns," the idea that rebounds is largely -- though not entirely -- a zero-sum game. Jason believes the Olajuwon story refutes the diminishing returns idea, because the rebound rates for the 4 other starting players don't change much in his absence. But to me it's a perfect illustration of the zero-sum idea, because the team rebound rate was essentially unchanged without Olajuwon.

To be true, the zero-sum argument doesn't require that the other four starters obtain the rebounds when a star rebounder leaves the court. It simply says that the team -- including the star rebounder's replacement -- will get nearly as many rebounds no matter who is on the floor (within reason). And that's exactly what Jason's story illustrates. The fact that a 6'-8" bench player near the end of his career can replace a 7-foot all-star center, with no net loss of rebounds, is hardly a vindication of Berri's analysis -- it's more a refutation of it. According to WP, Olajuwon was creating over 4 rebounds per game above an average center, worth about 10 wins per season to his team. Thanks to Jason, we can see that wasn't really true.

Perhaps you can communicate this important clarification to Berri and Jason, so they will better understand the zero-sum argument. Even if they aren't persuaded, at least they can then engage the actual criticism being made.

Flint · Joined: 25 Mar 2007 Posts: 112

Guy - The point of the post is that the Rockets were able to replace Olajuwon's rebounding. Larry Smith was a better rebounder than Olajuwon in his career, and in that season, even at the end of his career, he was as good in terms of rebounds per 40 and rebound rate. But Olajuwon was a much more prolific scorer than Smith. That is the major difference between them (although blocks and steals look very significant also). Ergo, how hard is it replace scoring? If you substitute a low usage player for a high usage offensive player, how hard is it to make up the scoring slack. The answer, in this case, and you would argue the point of course, is not very hard. How hard is it in general to replace scoring, as opposed to rebounding? It's an interesting debate I think, and I know where I stand at the moment.

This is argument from anecdote, which I of course love, and you could probably employ it to your advantage by finding a case that makes your argument. This one doesn't though. It's not a test of the case that if you put in an average rebounder in Olajuwon's place, you wouldn't notice the difference in the teams rebounding margin, because they didn't replace him with an average rebounder.

A better example for you might be:

Eddy Curry is a bad rebounder, perhaps the the worst rebounding starting center in NBA history. He increased his minutes dramatically last year, his rebounding numbers got significantly worse from the year before, and the Knicks still improved their defensive rebounding mark. How does this work? That seems to be the gist of what you are saying. Other players simply picked up the slack, as Q, Lee, Balkman, etc did. What does this say about Berri's view of rebounding etc etc?

I confess to being a bit puzzled by that. But what does determine a team's rebounding margin if not the proven abilities of the players on the court? It seems logical to me that the more players you have on the court with a proven ability to rebound, the better your rebounding margin will be, and the more likely you are to win. And that is the logic employed by the WOW. That may be wrong, I would be happy to see the case against that statement. It may be fairly random, or depend on coaching, or the mysterious way the players work together on the court, i don't know. But I will need a bit of persuasion. While there is significant variation in rebounding margin in the NBA, player rebounding totals seem to be quite consistent across time and teams, when adjusted for age and pace. There are differences of course, diminishing returns as Berri says, but not huge differences. Jason Kidd has always been a great rebounding point guard, probably the best ever as a pure point. Last year, he averaged 8.9 per 40, beating his career high at age 33. Clearly this has something to do with his teammates, the absence of Jefferson and Kristic. And when you consider the fact that his WP was the best in the league last year, and significantly higher than what he had posted previously in his career, you take that into account somewhat. But that doesn't change the fact that Jason Kidd is a great rebounder and had a great season last year. Is it really a coincidence that the Nets are the third best defensive rebounding team in the NBA after being the ninth best last year? What exactly does this have to do with Kidd? And how much does it affect their win total?

And why is it that Mikki Moore's rebounding average didn't skyrocket last year stepping into the same void Kidd was operating in? His rebounds were actually lower, per 40 than in the two previous seasons.

Guy · Joined: 02 May 2007 Posts: 128