seventhinningstrecth - those things you list as concerns appear to be outside of your son's and your control. Worrying about those things will only detract from the task at hand. Life is unfair and especially baseball. Maybe the coach is going off the radar gun for the time being and not the stats. Maybe he is going to give the high velocity guys the long leash even though they can't hit the broad side of the barn for the time being.
The best thing you can do for your son is to encourage him. He cannot control what the coaches decide to do. He cannot control injustice. Leave these things to God. Encourage your son to be ready for one opportunity. That is all he can control. Also, as hard as it is, encourage him to root for those kids who are struggling in front of him. That kind of good vibe has away of turning around as a blessing for your son. Focus on attitude and effort and leave everything else go. Those are the keys to success at baseball.