I hate curveballs for youth. I think it not only hinders a kids pitching ability it hurts their arms. Just my opinion. What I do think is kids that play more ball and work at the game year round are less likely to get hurt than kids that sit on their butts all year and then show up at tryouts and air it out trying to impress. Hey we play HS FEB - May. Then we play Legion or Select ball from June - August. Then we have our off season conditioning sessions untill Feb. There are periods of time we take off from throwing but we are doing plyos and strength training. Ive been coaching HS baseball for several years and knock on wood we have yet to have a TJ or a Rotator problem. Now maybe we have just been lucky probaly so. But I would rather have a well conditioned arm on opening day than an arm that has been working a remote controll or a video game.