If he has little/no control, he's not going to pan out in the majors.
Remember the early part of this decade? Dan Wright supposedly had the best stuff in the Sox' farm system (and he really did have some great tools... good velocity, and when on, he was VERY effective).
Where is he now?
Only pitchers thrive in the majors. Throwers tend to fizzle. It's all mental and based on control. See mitt, hit mitt. 'Nuff said.