He HAD all the potential in the world. After tonight, perhaps he still HAS it, but that remains to be seen.
His stuff was dominant. He was filthy. He was spotting his pitches well, and his velocity was up there. I think most of it is in his head. If he can get past the mental blocks (which is a big if) that is 90% of the battle. He also seems to have erratic release points, which is causing him to be wild. But if he fixes the mental, I have no doubt that Petterson can help him with the physical.
He may very well never put together a winnings season with an ERA below 5. He could be out of baseball by his late 20's. (See Ankiel, Rick) He has all the talent in the world, but whether he harnesses it or not - only time will tell.
But tonight sure was impressive to watch.