Coaching can be very subjective. I played for a coach who only spent time and kissed butt with the most gifted/talented players (American Legion Baseball). One player, for sure, is in the Baseball Hall of Fame. Some of the players he ignored (just OK in his mind), ended up with college scholarships, and two of the others made it to the Bigs. He made some errors.
I was in one job where I was fired (subjective boss). I then went to a competitor in the same town, took over $100,000.00 worth of business with me (1970's) and almost ruined the business that fired me. (It was only a FOUR hour job). Obviously, the creep that fired me made a wrong business decision. He was later fired, by the owner, because of his blunder.
My son has been working (entertainment) since he was NINE. He's now in college. Some employers think he's a big deal, etc. Others, won't hire him because of his look, color of hair, non-freckles, not street enought, doesn't look like Emenem,
blah-blah, whatever. That's really subjective, 'cause the next week he can be hired by someone who wants exactly what he brings out on an audition. Talk about subjectivity. He's been turned down for work (literally) HUNDREDS OF TIMES, and in his business is considered successful. It really brings out a person's character to be turned down that many times and keep fighting back. Tell your son not to give up (like others have said). But in the same breath realize the coach could be wrong.
You only hope that the coach, boss, casting agent, etc., is GOOD and Fair. It doesn't always happen.
I think it's a parents job to guide their kids, at least through high school, and make sure that whoever is laying the smack down on your kids is doing his or her IMPARTIAL job. IMO, regardless of how intelligent, kids really don't start putting things together until they get out of high school...in some cases wayyyyyyy later. Give 'em help if you think it's called for.
Coaches, bosses, doctors, attorneys, people in power, shouldn't be accepted as necessarily being in the right, just because of the position they hold.
Bill Gates even said, "Life isn't fair." Maybe he should have added, "It's SUBJECTIVE...that's why it isn't fair."