emotional 12 yo

We have a 12yo son who has played baseball since he was about 4 or 5. He LOVES the sport and sports in general. He is a decent player--not the best, but one of the top players. He's played all-stars 2 years when he was in PeeWee league and this is his 2nd year in PONY. He is generally a happy kid, and a good sport, but he's very competitive. He simply cannot handle bad plays or bad calls. He does alright for a while, but then he just falls apart. Last night's game ended in a loss for us (after many errors on our team's part) and happened to end on a bad call from the ref (from our perspective, of course). He cried, threw his hat and glove and got very upset. He can't calm down. This has gone on for years. We've punished, threatened benching (and he's been benched during all-stars for this behavior), sought counseling, bought books on the mental aspect of the game, and pretty much tried every angle we can take. I'm curious as to others' perspectives: should he be outgrowing this? how should we respond? what should his coach do?

He really seems to not have control over it, but we can't continue in this fashion. I'm ready to tell him he can't play anymore and really follow-through with it! But we have to finish out this season, so thanks for sharing your thoughts on this.