#3 Nikola Vucevic
Vucevic already excels in two specific categories. He is an elite rebounder (eighth in entire league last season in rebounds per game, 11.0) and he is a superb pick-and-pop offensive player because of his consistent 15-to-18 foot jump shot.
Vucevic hopes to be more of an enforcer in the paint. Rim protection and defensive intimidation are two integral areas at his position. By enhancing his status in those fragments of the game, Nik would become far more dominant. It would also be encouraging if he adds some power to his already effective finesse post game.