The biggest area he needs to improve in is decision making. I recall some posters here saying he needs to play more freely and not worry about making a mistake. I think the opposite. He needs to play more disciplined.
He could learn something by watching Melendez. RJ is very focused in his moves with little wasted motion. When he puts the ball on the floor, you can tell he knows what option a, b, and c are.
Outside shooting and strength would obviously help him also. He can play in the NBA, but he needs to make a big leap before that can happen.