My son is playing his first year of kid pitch in a Columbus suburb. He plays on a team of really good players. They are beating the snot out of the other teams, and are almost all third graders (just finished) in a league of 3rd and 4th graders.
My son has Asperger's which is a mild form of Autism. He is a pretty poor player, and uncoordinated. He can actually hit decently, but runs incredibly dorky and slow, fields poorly, throws like a girl (sorry about the statement, but I wanted to give the view), and just doesn't get the basics of the game. He doesn't know when to run or hold on a base, or what base to throw to. Some of the other players on his own team have started laughing and making fun of him. Particularly, two of the best players on the team are doing this including the coaches son. The coach is a decent guy, and admonishes them occasionally, but he doesn't go the extra mile to stop it. Confounding the issue is that we tell no one of his true problem. He has enough issues, without people ostracizing him because of his diagnosis. He is quite smart, does well at school, and is mostly well liked by his school mates. We took him out of the public schools and put him in an exclusive private school. We did this so that he would get more individual instruction (10:1 student to teacher in the classroom vs 24:1 in the public schools). He does well in this school, but a number of parents from the old school are upset that we "abandoned" the public school. He plays baseball with the kids he went to public school with, and this is really his last tie to that group. He really likes these kids, and wants to play ball with them. His condition makes it so that he doesn't really get that the others are making fun of him. He wants to continue playing, and so far hasn't said he is upset about this behavior.
My instinct is to go to the coach and complain, but I don't think it will be in my son's best interest. I don't think the behavior will stop, but only go underground and be even harder on my son. If I fly of the handle, yell, chastise, or anything of the sort, I don't see it going well.