I think it's about understanding the game, and the purpose being served. Porcello had to hit Youk because his guy got hit. Youk had to charge the mound because he'd been hit 2 days in a row. I don't think either move was done out of "rage", it was done because that's the accepted way you get your point across.
Similarly, in the KG/McDyess example given above, the person that says KG never wants to fight is absolutely right. That isn't the purpose of his glower. His purpose is to intimidate, to cause someone to be hesitant to make their normal moves. If that person gets so far out of his game that he wants to escalate it to a fight then KG wins, as long as he doesn't fight back. Unless you're an expendable enforcer, in today's NBA a fight is never the desired outcome.
In both cases, it's about knowing the rules, knowing the message you want to send, and executing it. It's not at all about rage, revenge or being a pansy.