Texan,
Thank you for proving my point. The key is in the instruction ie. Coaching. Watch the games at your local park next time you go. See how many kids throwing fastballs muchless anything else are throwing incorrectly. I have seen coaches try to teach an 8 yo to throw a circle change. Hell their hands weren't even big enough to grip the ball correctly. If you can't grip it correctly, how are you going to throw it correctly? There is no way you can keep kids from throwing junk but you can offset it by teaching correct technique when they become interested in it and are physically capable. My kids half brother told a DII coach he throws splitter, slider, curve and knuckleball and he is 6. Do you think I would teach him those pitches now? No way! If I were his Dad or coach, I would tell him I would send him home if I caught him trying to throw those pitches because in his mind, he thinks he can. Will that stop him 100%? Hell no. But when he is able to correctly grip the ball, and can continually demonstrate proper technique, then I have offset alot of problems. I can assure you I can teach a kid improper technique and see problems immediately and that does not only apply to pitching. To my final point of the topic. If a 13 yo is phyically capable,has proper instruction, and can demonstrate proper techinque repeatively, then let him/her throw it but control it. I think the concern is not the pitch (if above applied) but how many innings a kid that age pitches. There is your real concern.