Injuries often times can be flukes. A twinge in the elbow can be the result of one pitch. A pain in the shoulder can be one pitch (like Sheets) or a million pitches. When a person walks along, they can take a funny step on the sidewalk, and severely roll an ankle. I had a roommate in college who hurt himself on my birthday, on the way to a restaurant to celebrate. So on my 21st bday, I had 1 beer, and the beverage I had as midnight passed was a frosty from Wendy's, as I was tired of waiting in the ER and needed a tasty treat to celebrate my bday (we made him go to the ER...he just wanted to put his foot up and for us to give him a bottle of cheap wine). My point is that some injuries truly are preventable, some injuries are not. I've had one serious injury in my entire life of sports. Yet I'm avg build (at best), 5'11" (6' in golf spikes), and ALWAYS was the least flexible kid on my teams going back to when I was 5 years old. Yet the only injury I've had that lasted more than 1 day was when I dislocated my left shoulder trying to kill a moth (why I now bat lefty in whiffleball). I could have had a whole team of experts stretching me each day, following me around, and monitoring my progress. Yet there's no way anybody could have anticipated my friend would have chronic ankle problems because of that one night, and there's no way someone could have told me how badly that moth would make me hurt. While I like high school arms, my only concern with them is that bodies change. When I was 17/18, I was 5'10" and about 180. When I was 22 I was 5'11" and 200. That may not sound like much, but that included my shoulders broadening tons. My body shape completely changed in those 4 years, as I went from being called skinny/scrawny to being told I looked like I played fullback, offensive line, or linebacker. So my concern with all pitchers (HS and college) is that between 17 and 22, a lot can change.