To be fair to Kessler we haven't really asked him to do anything more than put-backs or dunks. We don't pass him the ball with his back to the basket at all, so we really don't know what he could do with it. That might be because he simply cannot do anything with it and the team knows that, or by design as it isn't his primary function when he is on the floor.
There is a little more in this than just put-backs, although put-backs and dunks are still 80% of his highlights, but he has a few nice jumpers and some nice shots from 5-8 feet in, including a couple of lefty hooks, and some reasonably nice 3 pt shots in there. I wish we would let him get the ball down low back to the basket so we can see exactly what he could do with it, even if he fails miserably. He needs the touches and chances to develop some confidence.