Raw plus/minus is nice, and I think interesting, if not statistically significant, for an individual game. But step two is to calculate an on/off rating a la the work Roland Beech does on NBA players.
This kind of analysis is problematic for star college players, because many of them play nearly all of their team’s non-garbage time minutes. We need a pile of data in the off category to make the results meaningful.
It just so happened that when the Pittsburgh Post Gazette’s Ray Fittipaldo wanted to step outside the box and do a story on the plus/minus concept, it gave me an opportunity to carry out this kind of analysis on a team where the star player does get some meaningful time on the bench. Aaron Gray is widely thought of as All-American/Big East POY material, and yet he averages 29 minutes a game. Not surprisingly, on/off data shows that Gray makes a huge difference to Pitt.
With Gray on the floor, Pitt is a +17 per 40 minutes, and with Gray on the bench, Pitt is -2. So over 40 minutes, Aaron Gray is worth about 19 points to Pitt. In his typical 29-minute game, he’s worth about 14 points. Basically, if Pitt had lost Gray to a season ending injury during Midnight Madness, they’d have a sub-.500 conference record. Which makes sense when you consider that Gray’s rating dwarfs any other Pitt player. Antonio Graves came in a distant second with an on/off of +5.
Not that this is particularly shocking, but it does illustrate the value of such an analysis in showing a player’s worth to his team. And keep in mind the value we are talking about is realtive to the team. Gray has no viable backup, thus he is very valuable to the Panthers. If we ran the same kind of analysis for Ohio State, I wouldn’t be surprised if we found out that Greg Oden’s value is in the single digits, partly because his replacement, Othello Hunter, is a solid player himself.
Check out Mr. Fittipaldo’s article for the rest of the details. (My favorite part of the article is the caption on the Aaron Gray photo – “Aaron Gray and the Pitt Panthers are still a good basketball team.” It’s almost like the captioner spent the week being endlessly harassed by a bunch of Louisville fans.) The complete list of Pitt on/off data follows, through last Monday’s Louisville game.
On Off Diff Gray +17.4 -1.7 +19.1 Graves +13.6 +9.0 +4.6 Cook +13.7 +10.2 +3.5 Fields +13.0 +10.5 +2.5 Kendall +12.2 +12.6 -0.4 Ramon +9.1 +17.2 -8.1 Benjamin +5.8 +15.5 -9.6 Biggs +5.4 +15.8 -10.4 Young +5.6 +16.7 -11.2