Putting pre-debut injury risks aside.... Does the fact that a guy like Kelley already has MLB caliber stuff and body help mitigate some of the risk? When people bring up his "now" body, that's usually a knock on him. Why wouldn't you want the guy who is guaranteed to have the right size over the guy you hope grows into that?
There is a very good chance he is already maxed out which means he has to maintain his stuff for a long period of time while learning a breaking ball and improving his command neither of which are close to MLB caliber. It is much more likey that his stuff will back up during that time which is why teams look for projectable bodies that continue to get bigger and stronger. You want players who continue to get better and build up to the big leagues. Mick Abel is a perfect example of that.