I have to say, I respect Kyle a ton and am a big fan of his work, but I really think that is just insane to have youth pitchers throw year round without a break. If anything, their arms are overused well beyond what a pro pitcher goes through. After they pitch they usually play a defensive position the rest of a tournament, they throw an incredible amount over the course of a weekend between warmups, playing a position, pitching, then back to playing a position etc.... Sure some are PO's but most are not.... Factor in that their growth plates haven't closed, their mechanics aren't top notch, they are still growing which throws mechanics off even more
I think it is just insane, and doubt there is any data to back that up. It is theoretical, and theoretical is a big roll of the dice.