Thursday, June 18, 2009

Defense = (blk+stl)/fl?

The Search for a Defensive Efficiency Stat
One of the nifty benefits of Dean Oliver's Individual player offensive rating (ORtg) is how the number is useful for identifying how well (efficiently) a player converts possessions into points. As most come to understand however, that stat needs a context -- what role (major contributor? significant contributor? role player? limited role?) does the player actually serve in the offense. That question needs one (or sometimes two) more numbers -- the percentage of possessions the player gets when he is in the game, and maybe also how often the player gets a shot (FGA). Want to compare the conversion proficiency of a player who takes most of his shots inside the arc with one who takes a large portion of his shot outside the arc? Use the eFG% ((FGM + 0.5 * 3FGM)/FGA). Want to know how efficiently a player registers points when he takes a field goal attempt? Use the PPWS or True Shot (Pts/(FGA + 0.475 * FTA)...for the PPWS, which can then be divided by 2 to get the TS). And know that the offensive efficiencies are more easily identified and measured. Dean Oliver, author of Basketball on Paper, devoted a specific chapter ("Individual Defensive Ratings") in his book, to discuss the difficulties encountered when trying to identify (and collect/compile) stats that would be useful to measure defensive efficiency.

Magic Bullet or Magic Marker?
A stats geek (BadgerCane) over at APBRmetrics, proposed a statistic that divided the sum of a player's blocks and steals by the number of fouls he committed. I ran the numbers for Big East players for the last 2 seasons, looking only at players who logged 450 or more minutes (about 37.5% of the playing time at their position) in each season (2007-08 & 2008-09). The Top 30 players over the two season time frame...

2 Yr.
Hasheem ThabeetUConn1.875
Terrence WilliamsLVL1.439
Earl ClarkLVL1.368
Rick JacksonCuse1.275
Jonny FlynnCuse1.123
Sam YoungPitt1.113
Dominic JamesMU1.068
Hamady N'DiayeRU1.033
Jerome DysonUConn0.965
Stanley RobinsonUConn0.955
Will WalkerDPU0.948
Geoff McDermottPC0.940
Paul HarrisCuse0.938
DeJuan BlairPitt0.936
Jerel McNealMU0.934
Jeff XavierPC0.921
Jeremy HazellSHU0.899
Weyinmi EfejukuPC0.892
Jeff AdrienUConn0.868
Alex RuoffWVU0.860
Jessie SappGTU0.860
D.J. KennedySJU0.856
Corey ChandlerRU0.852
Eugene HarveySHU0.843
Paris HorneSJU0.833
Dante CunninghamNova0.814
Dwayne AndersonNova0.811
Ryan AyersNDU0.797
Arinze OnuakuCuse0.778
Jerry SmithLVL0.755
Craig AustrieUConn0.754

All the Usual Suspects...and a Few Surprises
>1.0 is very good. If the Big East's Defensive Player of the Year (2 consecutive seasons) -- Hasheem Thabeet -- does not surprise, the fact that he registered nearly 2 blocks/steals per foul gives pause to think. Using the stat to measure magnitude (is Thabeet twice as "defensive" as Austrie?) is hardly appropriate, but the list is certainly studded with names known throughout the conference for their defensive abilities and athleticism -- James & McNeal from Marquette, Williams & Clark from Louisville, Pitts' Sam Young and DeJuan Blair (both gone to the league this post season), Flynn, Jackson, Harris and Onuaku from Syracuse, and virtually the entire Connecticut starting line up (Thabeet, Adrien, Robinson and Dyson...only Price, who was ranked #35, is missing -- small wonder the Huskies, along with the Cardinals were far and away the best defensive unit in conference games last season). Villanova's Dante Cunningham and Dwayne Anderson, two well regarded defenders on the Wildcat squad for the past two seasons, are also ranked in the top 30.

On the other hand when Jeremy Hazell and Eugene Harvey from Seton Hall are mentioned, it is generally not for their defensive exploits. Hazell is regarded as a prolific scorer. Weyinmi Efejuku, Will Walker, Jeremy Hazell all combined good (to excellent) steal rates with a lower than average propensity to commit fouls, attributes that suggest good defensive skills.

A Few Other Wildcats
A few of the other squad members who logged the requisite amount of time...

2 Yr.
Scottie Reynolds380.706
Reggie Redding470.616
Corey Fisher500.552
Corey Stokes640.441
Shane Clark660.390
Antonio Pena710.341

For Reynolds and Fisher, whose steal rates were comparable to Will Walker's, Geoff McDermott's and Jeremy Hazell, the key was fouls. Both players were whistled often enough to diminish their ratings. The same holds for Pena and blocks -- the Villanovan had a block rate comparable to Geoff McDermott (his ranking was a combination of blocks and steals...) and DaJuan Blair, and better than Jeff Adrien. But the Wildcat also fouled at a higher rate than those three players.

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