I'm sure Zach Randolph doesn't have a chiseled body, and he's done pretty well in the NBA. In fact, he known as a gut that doesn't get pushed around easily.
When I look at Kevin Love he doesn't look exactly "packed" to me either.
Sully's power comes from his lower body, if he tightens up his upper body a little, he'll be fine. Don't forget it's only been 6 months since he began. With Sully the question is will he continue to work.