I tried to give you the benefit of the doubt when you first posted here, but it's getting more and more difficult.
You have tried to place blame on almost every possible outlet: your son's coach, the assistant coaches, his catcher, and now every single one of his teammates. You need to think about what you are teaching your son. You cant always blame others for what goes wrong. Is his coach a jerk? Maybe. Did the catcher work in sync with your son? Maybe not. Did the team conspire to throw the game in order to spite your son (and him alone)? I seriously doubt that. You need to show him that life isnt always fair. That there are good outings and there are really rotten ones like he just had. Even major leaguers can get chased from a game in the first inning, but you never see them in the press conference blaming everyone else, do you?
I am assuming that your league has the minor division for 9-10yo, majors for 11-12 and then the 13-14 league? If that is the case, then it doesnt matter how many years you spend in "majors" so long as there is a team in the higher league that wants him. If you and your son are still having problems with the coaches in that league, you may want to move to a different league in your area (like PONY). That way he can get a fresh start without having any biased coaches or expectations.
And dont let him forget that this is a game, and games are supposed to be fun.