In my opinion Sully will turn out to be one of the best power forwards in the league and soon. He's just come off an offseason where he had back surgery, and has always played out of position in the NBA because of our roster is unbalanced.
He's quite young, give him some time to really train himself and his body, stabilize his role and position, and he'll show what he's made of.
I really like him. Not saying I wouldn't trade for Kevin Love, but I think he'll be someone who'll be plenty more than he currently is.
In part he's show he's a fighter and competitor, very good rebounding big, good passer, and very capable in his defensive rotations.
He's currently very much an underrated asset.