APBRmetrics

kbche · Joined: 19 Jul 2005 Posts: 51 Location: washington d.c.

Hi Dan,

I looked at your top 6 defensive centers, power forwards, small forwards, shooting guards, and point guards. My observations are as follows:

1. Only 3 of the 30 players have ever won a championship (correct me if I am wrong).

2. 23 of the 30 players played on teams in the 04-05 season that made the playoffs.

3. Only 3 of the top 6 small forwards were on playoff teams in the 04-05 season. This was the lowest percentage of all categories (all other categories indicated that 5/6 played on playoff teams).

Thus the top defensive players were generally on the better teams. Are the players making the team, or are the teams making the players? How can we tell from your model?

Have you considered different OLS estimates to improve the goodness of fit? The assists made and points scored are not independent variables and should probably be treated as such in a model. A player in a particular play can not score points and an assist on the same play. Does your model account for this?

You added a appreciation/depreciation factor for players. How was this developed? A player would have to be on the same team with the same team mates for successive years, and the players' performance would have to be normalized.

Kimberly

Dan Rosenbaum · Posted: Tue Aug 16, 2005 11:55 pm Post subject: Re: Defensive Player Ratings

JPOP · Joined: 07 Aug 2005 Posts: 5

Hey Dan,

I'm pretty impressed with the overall performance of your defensive ratings. I keep finding aberations with multiposition players although I'm only looking at a small sample. Some of these multiposition players defend out of position because of a lack of team depth, always defending the best wing or post player or to match up with the opposition.

There are quite a few players who defend well at their primary position, but don't defend well at a secondary position. Not everyone can provide the multiposition defensive flexibility of Garnett or Kirilenko to be nearly equally effective defending two positions. Just the same they may be a teams best option to defend a certain position for a length of time throughout a game.

These multiposition players are very likely to create some year to year noise defensively as their roles may change with additional personnel on their given team. Primary position defense is much less likely to spike from one year to the next than what is seen by a player having a major shift in the percentage of minutes the player needs to stray from defending their primary position.

There are quite a few examples, but here a few primary ones.

Robert Traylor is an awful defensive player when matched up with centers. At the same time he is more than adequate defending power forwards. His work at center was so bad, it pushed him into the bottom 10.

Eric Snow has made a career out of his defense. With Iverson he often cross matched defensively doing a great job at defending shooting guards. The past year in Cleveland, and generally not needing to play a cross matching game, when he defended shooting guards his defense was stellar, when defending point guards, he was incredibly average.

Darius Miles cracks the top 10 (#3) at small forward likely due to his prowess at defending the rangy fast/quick power forwards of the Western Conference. I guess some coaching genius by Cheeks and an assignment Miles never had in the past. That could explain the somewhat high Standard Error.

It seems to me having some positional ratings for multipositional players goes a lot farther than lumping together their on-court performances. There are too many players who have either offensive or defensive efficiency at one end of the court while squashing it with not enough length or bulk to be effective at the other. This is also the type of information that escapes more than a handful of coaches with their substitution practices.

Again, this is a great set of ratings and has some true promise. I look forward to seeing the whole list some day soon and believe there are quite a few coaches out there who would be shocked if they were aware of some of the shortcomings their substitution patterns bring.
_________________
7 or more interrelated variables become art although I applaud the efforts of those who try to put science behind them.

Dan Rosenbaum · Posted: Wed Aug 17, 2005 12:26 pm Post subject:

JPOP, these points about multi-position players are another reminder of how important context is. Put a player in a role for which he is not well suited and his plus/minus rating is likely to suffer.

But I am not sure the year-to-year variation in adjusted plus/minus ratings is greater for multi-position players. Players who are well suited to just one position are often forced to play a different position, and for that reason their plus/minus ratings can be all over the map. Dwight Gooden is a good example. Memphis and Orlando tried to play him a lot at the 3 and he had horrible plus/minus ratings. Put almost exclusively at the 4 with Cleveland and he looked a lot better.

Recogninzing the roles which a player can excel most at is where a good coach or a good stats analyst can be of tremendous value.

Ben · Joined: 13 Jan 2005 Posts: 266 Location: Iowa City

Nikos · Joined: 16 Jan 2005 Posts: 346

JPOP · Joined: 07 Aug 2005 Posts: 5

back2newbelf · Joined: 21 Jun 2005 Posts: 274

@dan rosenbaum:
-could we get the numbers for artest from the seasons he played? just the ballbark would be alright...
-would the defensive adjusted +/- ratings and the "normal" adjusted +/- ratings make it possible to accurately guess the offensive adjusted +/- ratings? for example: if michael redd has an average "normal" rating, could we say that he is an outstanding offensive player, and if so...get an accurate offensive rating?

kbche · Joined: 19 Jul 2005 Posts: 51 Location: washington d.c.

In a regression analysis, you are assuming that Y is some function of a set of X variables. A regression can be performed with any set of variables. It is up to the developer to verify that Y is actually a function of X variables, and the type of function must be specified.

Eli W · Joined: 01 Feb 2005 Posts: 402

One thing I've often wondered is how well the players themselves can tell who plays the best defense. The all-defensive teams give us a sense of the general perception, but what about a player's teammates, opponents, and coaches? What do someone like Ben Gordon's teammates think about his defense?

In Dan's rankings, Darius Miles rated as the third best SF defender. He has a high defensive statistical +/- and has had a very good defensive adjusted +/- each of the last three years. But here's what his new assistant coach Maurice Lucas had to say about his defense: