An 11U player isn't being paid to play. He's also more vulnerable to arm injury since he's a growing kid. Pro and college pitchers pitch through pain to a point. High school pitchers will do it in a big situation. But even then it's monitored closely. And it depends on what kind of pain. The only thing you need to tell your son is if his arm hurts tell the coach. If you think the coach is a moron removed your son from the team.