Nice thing about Bender is that he plays defense consistently. He still makes some mistakes, but for the most part, you can count on him defensively every on every possession. Offense will come. His three-point shot keeps getting better, and he shows the ability to drive to the hoop every once in a while. He just needs to keep being aggressive and confident, and he will be fine.
As far as rebounding goes, I am not sure what his deal is. He blocks out well enough, and the Suns centers have been doing a good job rebounding. Offensively, he plays too far away from the basket. Now, that's fine, but when the shot goes up, he really needs to go for some offensive rebounds.
EDIT: I still maintain that he will be most successful as a Center. He still needs to add twenty pounds of muscle, but he will be more effective as a Center than anything else.