There are 1000's and 1000's of pitchers that don't end up with Tommy John surgery. I just don't think you can look at a kid and say "Oh, it's because he threw xxx innings and played SS on his off days". My son was a pitcher, catcher and SS growing up in his local leagues. IF, OF and P on his first 3 years of travel on a team that carried 10 kids (so essentially no innings off over a 65 game season and he also had local rec ball). Heck some days he's play games for both teams. His first year of playing both travel and local rec leagues he played 97 games (he was 10). He was crushed that the last tourney got cancelled to keep him from 100. 11U and 12U I'm gonna guess he played 80 games each summer...the kid would play for anyone who would take him. 13U & 14U probably 50-ish and 15U & 16U (including HS and fall ball) probably 75+. 17U I'm gonna guess 50-60. 12U and up he played SS and P...and sometimes caught. Yes he would play SS then go in in relief....he would also start on the mound then go to SS or even catcher. He never had ONE arm issue....never iced....not even now that he's in college. If any one was every a poster boy for what not to do....it was him, but he's fine. I guess I'm just saying that you can't just automatically say "if a kid throws too much he's gonna have TJ". I'm not a doctor....I don't know what causes it...but just playing a lot of ball doesn't guarantee it. Rant over 
