At what level do position players that also pitch stop pitchingand just play their position.
A few things:
1. My son didn't throw anything overhand from october-february while 15u and below. Result was his counterparts pretty much all got hurt with growth plate issues, arm fatigue, little league elbow, stress fractures...and on and on. He has not. The worst time for arm injuries is 12u-14u, they are just very fragile then, shutdown is vital for health.
2. Arm programs absolutely have their place, but I'd wait until 10th grade.
3. The game tells the kid when they are a PO or a two way player, or a position player. My son was that kid who played every position. Wherever they pulled the pitcher from he could play there. He also played a lot of 1B and OF. He has decent speed, decent bat....but he started pitching at age 12, and there was something special there.. Here we are as a junior in high school, his last summer, and he wants to play outfield and not just pitch. He's going to be a pitcher in college, he has accepted this, but for his last year of travel ball, he is having to drop down a level so he can play outfield part time. So, when does the divide happen between being a PO and a position player, I'd say it happens when you let it happen, and what you are willing to do to remain not just one or the other.
4. As they grow they have to relearn hitting and pitching weekly! I am not joking. A poor outing now means nothing. How well would you do either if your one arm or leg was now an inch longer than the other one?
5. Be wary of coaches who know it all, they don't, regardless of their "qualifications". Puberty is a literal game changer. Do not allow your child to be pigeon holed into any one position. That would be a mistake. For all you know the only way for him to play HS ball is to be a third basemen, do you really want him to tell the high school coach he only plays outfield?