The plus-minus, as with all plus-minus numbers, must be taken with a grain of salt, however. Take Evan Turner, the presumptive No. 2 pick out of Ohio State. Turner was college's National Player of the Year. No offense to his teammates, but effectively, Evan Turner was the Buckeyes. Why, then, does Turner have the second worst plus-minus -- minus-7.8 points per 40 minutes -- among all players in DX's 2010 mock draft?
I imagine the timing of Turner's back injury has something to do with it. Turner fell hard on his back early in a game against Eastern Michigan, fracturing his vertebrae and knocking him out for six full games. That happens to coincide with the end of the cupcake portion of Ohio State's non-conference schedule. Without Turner, the Buckeyes managed to run up the score against EMU (outscoring the Eagles by 41 points in the 33 minutes following Turner's exit), beat Presbyterian by 30, Delaware State by 26 and Cleveland State by 13. Ohio State lost to Butler, Wisconsin and Michigan in there, as well, but those cupcake matches sure inflated OSU's non-Turner points margin.
In fact, when you remove Eastern Michigan, Presbyterian, Delaware State and Cleveland State, the Buckeyes outscored opponents by 19.1 points per game when Turner wasn't on the floor. The Buckeyes outscored opponents by 22.5 points a game when he was on the court. That +3.4 plus-minus looks a lot better for Turner, though it's still below about two dozen prospects. And that, frankly, is a bit concerning, especially considering Turner's subs weren't exactly world-beaters.
This is why, to me, plus-minus is useful. It raises red flags. Turner's plus-minus red flag can be mostly dismissed. But at least it's good to know it's there.
(Seriously, check out DX's new data. It's intriguing as all get-out.)