Would you mind telling us his age? I love the arm action, very efficient. No really, if anything needs to be fine tuned, it would be in the "off season" or if he starts getting in trouble often. Remember that no matter how much a coach or a dad believes in a player, you can't go any further than the kid's will.
Great curveball, i would have loved to meet him in real life, I have taught some pretty successful circle change up to some pitchers with similar delivery to the point where one of them literally stopped throwing breaking balls and went fastball-changeup right until second year of Junior AA.
Does he throw one?