回复：我不敢提“racies”这个词。儿子确是team 里唯一的老中。

You don't have to mention "race" issue here, considering the coaches are all volunteers (or maybe not), but fair is fair. It's hurtful to the child if they don't treat the team members fairly.
I cannot understand any coach would do such a thing to let a player just sit aside and watch the whole game! At least the kid should be allowed to play part of the game.
As a parent I would talk to the coach (I actually did, many years ago). If you don't talk to them, they would not realize it's a problem and may repeat the pattern. They may not neglet your child on purpose.
On the other hand, it's a good chance for the child to learn to deal with this kind of disappointment in life.