Maybe I'm getting old, or not into stats enough to try to understand what ortg, or whatever other metrics are used on here, but I think the +/- system makes a lot of sense (unless certainly players go in and out at the same times). If used properly, it can keep coaching from playing "favorites". What matters is, do they help advance their team, or not.
If you asked me, I would have said that BHH had the better game or at worst about the same, but this metric says otherwise. I think this is part of why Plavsic played, and BHH didn't so much, in the 2nd half. I guess BHH's defense/rebounding is still lacking, similar to the situation with Powell.