APBRmetrics

Mike G

From the Journal of Quantitative Analysis in Sports:

http://www.bepress.com/jqas/vol3/iss4/1/

Using Box-Scores to Determine a Position's Contribution to Winning Basketball Games

Garritt L. Page, Gilbert W. Fellingham, C. Shane Reese

The study looks at boxscore totals for a game, by position, and determines correlations with winning. These are translated into value per item for some things -- FG, FT, 3FG, Ast, Stl, TO; and into value per .01 for other quantities -- OReb%, DReb%, FG%, FT%. The value is expressed as 'points per 100 possessions'.

This seems to place an entirely different scale on those stats considered as a % , so I'm listing them separately. (I realize I may be interpreting some of this wrong, and I have no idea about the methodology.)

Data were from USAToday boxscores, from the 1996-97 season. These boxscores don't list Blocks or 3FGA. 3FG were determined by (Pts - 2*FG - FT). Only starters positions are listed, so everyone else's position is lumped in under 'Bench'.

I've hand-entered the data, dropped some digits, and ignored the uncertainty ranges. Here, it seems, are the positions and the relative importance of the stats, arranged by position.

ziller · Joined: 30 Jun 2005 Posts: 126 Location: Sac Metro

The conclusions drawn seem a bit stretched to me. Particularly w/r/t assists: There are causality issues without doubt. The authors don't address (mention? sort-of, near the end) that assists rely on made baskets, which clearly have an impact on point spread. If PG #1 has 12 assists and PG #2 has 3 assists, and Team #1 wins by three... is it because PG #1 had nine more assists, or is it because Team #1 shot better (thus earning PG #1 more assists). We don't know based on these findings, I'd said.

This issue also screams out with steals from the center position. Is that indicative of a defensive center with good hands, or a poor offense on the other side? Has anyone ever looked to see if steal rates for centers (or even PFs) are consistent on a season-by-season basis?
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Mountain · Joined: 13 Mar 2007 Posts: 1527

I mentioned the original thesis that served as the basis for this slimmer, revised article 2-3 weeks ago (among others) in the New England Symposium thread.

http://tinyurl.com/235wy6

I speculated it deserved to appear in a journal, perhaps JQAS. The only comment at the time was from Mike G. joking about "the posterior means" I pulled out for ease of viewing for readers here. Now the article comes out and Mike has pulled the same set (with updated values) as I did. Kinda funny how that worked out. Good that the article is out there more clearly now to get whatever comments.

John Hollinger · Joined: 14 Feb 2005 Posts: 175

I believe the rebounds from guards is another area where this is an issue. Guards' rebounds tend to be almost entirely defensive boards; defensive boards, in turn, tend to require a shot to be missed by the opponent.

Mike G · Posted: Tue Oct 23, 2007 4:45 am Post subject:

Yeah, I thought these numbers looked familiar. Also, it's illuminating to sort and group them differently. Here they are grouped by event, sorted by position of 'importance':

Mountain · Joined: 13 Mar 2007 Posts: 1527

Thanks for the different data sortings. There are clues in there, though I don't know how much weight to put on the results.

Looking at these results and how specific teams were designed and operate may spur additional thoughts, new questions. Using Jorje's hoopstats.com tools in conjunction with the values on these tables, teams can be analyzed by position instead of by player, You can compare skill emphasis strategies suggested as being more favorable on paper, in aggregrate to what happens on the court with particular teams and players and ponder what to change...

A strong SF seems valuable, perhaps because it is comparatively rarer because of quantity of players that get that label and stronger correlation of skill & opportunity at other positions?