One subject I’ve seen addressed time and time again in the comments section is how to measure defensive ability. The topic arises shortly after I mention the three letters ‘P’, ‘E’, and ‘R’, which stand for John Hollinger’s Player Efficiency Rating. While Hollinger has done a great job in the first steps toward getting a player’s ability down into a single number, PER does a poor job in measuring a player’s total defensive contribution. Although it does account for blocks & steals, I think most of my readers are knowledgeable enough to know that this isn’t the best measurement of defensive ability. Bruce Bowen is the poster-child for PER’s failure. A uni-dimension offensive player (“go stand in the corner and only shoot if you’re wide open”) Bowen’s PER is usually among the league’s worst. However the Spurs’ guard-forward is considered among one of the best defenders at his spot, which some think overshadows his offensive liability.
This defensive conundrum is not necissarily caused by the game itself. While basketball does pose a challenge in assigning individual blame and credit, I’d argue that the primary fault is not the game, but rather how it’s being recorded on the stat sheet. In the Wizards/Bulls playoff series this last year, the NBA didn’t need to hire a host of experts to get better defensive stats. In fact they didn’t hire anyone. Kevin Broom, from the comfort of his own living room or maybe local bar, developed a simple method similar to keeping a regular box score, but on the defensive end. (BTW aspiring writers – if you want to get an article published in SportsIllustrated, that’s the way to go.). Since Roland Beech opened up 82games.com, there has been an increase in data available to the public to help come up with more information on a player’s defense.
This brings me to Dan Rosenbaum. APBRmetric members and 82games.com readers might recognize the name. Although the economics professor might be best known for his work on the monetary side of the NBA, he’s come up with something interesting: defensive ratings . Dan isn’t revealing his exact equation yet, but he’s come up with a defensive metric using 82games.com’s data. He’s only given rankings on a few players, and initial results pass the “laugh test.” The method seems to favor neither shot blockers nor man to man defenders, as both Ben Wallace and Jason Collins are in the top 5 of centers. I have to agree with Collins’ selection, because just like Bruce Bowen someone with a 9PER doesn’t get 30 minutes a game without being good on the other end of the floor. Rosenbaum’s part I is a teaser, just givng us the best & worst big men, and leaving out his exact method. Hopefully with the next installment, we’ll get all the rest of the positions, and maybe the whole list.
Oh and welcome to the blogosphere, Dan. :-)