Friday, March 27, 2009

John Hollinger Augments PER

He's added VA (Value Added) and EWA (Estimated Wins Added). I'm a little wary of the mis-interpretation of the latter's handle as PER* doesn't measure defense beyond one's steal and block rates but this should provide some help to those who never quite grasped that the "E" in PER stands for efficiency.

Sortable leader boards and what-not available here.

*As the man himself writes further down the piece:
So is Bruce Bowen the worst player in the league?

No. He has the worst VA because it becomes negative for players with a PER under the replacement level at their position. Of such players, Bowen has played far more minutes than the rest thanks to his on-ball defensive ability (which PER doesn't measure). Those minutes make his rating even more negative than the rest, dragging him to the bottom of the pile. For genuine awfulness, however, one could argue that Adam Morrison (-47.1) and Stephon Marbury (-1.1) have done as much to hurt their teams as anyone else in the league.
Further reading: Kevin Pelton compares EWA to his WARP.

1 comment:

Preston Heard said...

good link...I heard a good podcast with Bill Simmons and Hollinger talking about the deficiencies of the PER. As the quote about Bowen shows, the most glaring deficiency of it is the failure to account for defensive ability. However, a good point was brought up that the fault doesn't lie with Hollinger's formula, it's with the NBA's failure to maintain thorough defensive statistics. Simmons said that many teams record all sorts of stats that would be awesome to have (controlled blocks--as opposed to dwight howard blocks, that don't help your team at all because the other team retains possession; contested shots; charges taken; total turnovers forced; and many others I can't think of now), but these teams are unwilling to share those numbers with the public. For some reason, the NBA has been unwilling to devote the time and resources necessary to keep track of those stats, and until they do, we're going to have unsatisfactory player formulas like the PER.