Update (9:51 p.m.): Here's the full audio clip. He goes on for a very long time.
Brooks is angry about a lot of things, but most of all he seems to be upset that his team didn't show enough HEART. (Very original thing to be mad about, shitty baseball dude.) After laying into his kids about how they didn't play with enough GRIT, he just starts telling them to fuck off one by one. "You can't fuckin' dive for a ball in the infield? Fuck you! Can't make a routine play? Fuck you! You gonna fuckin' piss and moan at the fuckin' umpire? 'Nyah nyah nyah,' fuck you! Get off the goddamn mound! I want a man out there." He then notices that one of the players is slouching, and he just about has an aneurysm.
Once again, we are reminded that a Venn diagram of "high school baseball coaches" and "truly terrible rage-oafs" would pretty much just be a solid circle.