He overthrew a pitch and got hurt. That’s all. Keeping him Triple-A would have done absolutely nothing; you’d have to be an idiot not to see that he’s ready for the big leagues. He was getting his first taste of dominating big leaguers, and he wanted the whole damn cake. It was a mistake, he’ll learn from it.
You can sit in the passenger seat as much as you want and read as many books as humanly possible, but you have no idea what it’s like to drive until you get behind the wheel. Pitching for Scranton another month, 2 months, 6 months, whatever, would have done nothing but delay this injury until later in the year. It was a mistake brought on by lack of experience.