As I said in a game thread, his hands seem really weak and he exposes the ball too much. I think when he grabs a rebound he keeps the ball above his head and ready for a quick outlet pass, which also exposes the ball to be poked out.
IMO, he needs to pull the ball in and throw his elbows around to get guys off him. Secure the ball, then make the pass.
I don't know why he fumbles so many passes - it could be a vision thing. But he needs to look the ball into his hands, secure it, then make his move.