Sully's interior D has become good, and his rebounding ability is incredible. That stat definitely overrates him, as he doesn't do a great job on the perimeter, doesn't switch onto guards, doesn't break up transition plays, and he isn't an intimidating shot blocker. But he's surprisingly good at being in the right place to cut off penetration, and he has really good hands - he can get a hand on the ball before his man goes up for the shot, which mitigates his lack of explosiveness. And the really big thing is his defensive rebounding - he blocks out so well, and if he can get a hand on the ball, he's incredibly good at reeling it in.