It's the combination of pitching, lifting weights, year round sports, that finally ruins the arm. Younger kids should not be allowed to throw curve balls. Overtime, this puts a lot of strain on the "Tommy John" tendon. A change up is just as effective and does not cause the wear and tear on the arm. My son pitched a lot in travel ball and when he got in high school, there was constant use of the arm, whether it be weight lifting, summer varsity baseball, throwing footballs, spring baseball, etc..His arm never got to rest. Andrews Institute says that a kid needs to do nothing with his arm for at least three months out of every year. (thats not happening anymore)My son was clocked at 91mph as a sophomore in HS and by his third year playing at FSU, he could not reach 82! He underwent major shoulder surgery. The surgeon told us that he used to do one of these surgeries a year and now he does them everyday. He commented that it was complete over use of the arm while in the developmental stages. Fortunately my son bounced back because he was not a pitcher, and worked his way in to a top five round pick. A few weeks before the draft, he reinjured his shoulder. (career over)!! I know I am ranting, but I have seen first hand what can happen and do not wish this on any of you. Pro scouts would much rather have a pitcher these days that grew up in the North, playing hockey and very little baseball due to weather. Their arms are simply not going to wear out.