There are plenty of available ways for an athlete to embarrass himself on any given day.
He can insult a teammate or a coach (accidentally or on purpose) during a news conference. He can miss a dunk. He can get caught texting inappropriate photos of himself to someone who is not his wife, or forgetting the names of one of his many children.
But there is perhaps nothing more embarrassing that can happen to an athlete than when he injures himself throwing a temper tantrum.
The tantrums are problematic enough, but when you put yourself on the DL or season-ending IR because you couldn't restrain yourself from assaulting a wall/fire extinguisher/other person over something as stupid as a blown call or a ball that should have been called a strike?
You deserve to be kept out of commission for that.