It's the scoring differential when the player is in the game.
A +6 means for Sully would mean that the Celts outscored the opposing team by 6 points while he was on the game.
A -3 for Rondo would mean that the opposing team outscored the Celtics by 3 points when Rondo was in the game.
I get it but some of the plus and minuses are very deceptive because there are quite a few games I noticed that even though Rondo did real well in some games he was still getting minuses leading you to believe he wasn't doing well while in the game.
Thanks for the info
my understanding is that +/- (plus-minus) is a stat better used over time -- sort of like batting average in baseball -- AND when expressed as on-court vs. off.
Sullinger might be -20 for a particular game, but that could be for any number of reasons (tough matchup, luck, shot not falling, etc.). It doesn't tell you much more than David Ortiz going 0-for-4 in a game.
But taken over a season it provides a greater picture of value.
Sean Grande points out in
his interview with Jeff on the front page that Sullinger is +15 / -282 -- which means the Celtics have outscored their opp. by 15 points this season whe Sullinger is on the court but been blown out by 282 points when he's not on the court.
You could conclude - that for whatever reason - teh Celtics perform better with Sullinger on the court than not.
The reasons for this vary -- it could be b/c of Sullinger's direct impact, or it could be that his backup is so terrible that when he goes out there's a HUGE dropoff in talent, or some combination of these (and other) factors.