Dealing with a HS Dad Coach

Hey fellow coaches, while I've coached for a while and seen a lot of dad coaches, this is about a situation I have with my son and his current HS coach.

A little background: My son is in 10th grade (varsity) and he has a new HS coach who also has a son in 10th grade. We've known both the coach and his son for a long time and unfortunately the coach and his son have a long rivalry with my son. My son is the better player, and they've never been happy about that. But up until now it didn't matter -- lots of kids/parents don't like other kids/parents. But when my son's HS decided to make him the head coach, we now have a problem. We actually pleaded with the AD not to hire him due to all the past history, but the AD felt that "he's a professional -- he won't bring this with him to this team".

Pretty much every practice the head coach gives my son a hard time about everything -- every missed shot, turnover, etc... Even made shots get criticized for being "bad shots". HIs son, of course, gets heaped plenty of praise. It's gotten to the point where other players and the team manager are asking, "why does the coach pick on you so much?".

I tell my son "just keep your head up and play hard", and he's doing that. But it's hard telling him to do that knowing that it's not going to get any better. The coach can't not play him, as he's one of the best on the team, but he does work hard to keep the ball out of his hands and jump on any miss or mistake. I've had other HS coaches asking if my son would want to play at their HS, but we like the HS except for one thing -- the coach.

I figure this isn't a completely unique situation. Daddyball isn't new, and daddy ball where a kid of the team has a history with the coach's son can't be new either. I'd love to learn more from folks about how they've dealt with situations like this in the past or any suggestions for us going forward.