I think he's a lot more dark and twisty on the inside – between the daddy issues we exploit in fanfiction, and giving away Beth, I think Puck has a whole lot of hurt in him.
It's early in the season. They won't have a game for a few weeks, but they start practice early, because, face it, they need it. It starts Monday, two o'clock, and goes until five, when the new coach throws them into the locker room, gives them four minutes of hot water and has them all out and the place locked up by five fifteen so she can be home at five thirty for a television program.
Mostly, their practices are so disheartening, no one sticks around for too long after that.
He sits on the bleachers, watching the field. He's not used to this empty aching in his chest yet. So he sits and stares at the field, reliving past glories, when he was one of the stars of the team. It wasn't a lot of glory, and being the star of a losing team didn't mean much, but Lima's such a mediocre place, if you're above average at anything, you're pretty much a God.
Except singing. Singing isn't cool.
For some reason, he finds himself taking the stairs back down to the field, and he stands in the centre of the wide green battlefield, and thinks of Beth.
He screams.
It's brimming with anguish, pain, and hurt, and he's glad there's no one around to hear it. It doesn't make him feel any better, but it doesn't make him feel worse, either. Nothing makes him feel any better at the moment, so he settles for 0 steps anywhere instead of steps in the wrong direction.
He screams some more, and there's more pain buried in it.
Later, he'll tell his worried sister it was just a long practice, and he's just tired. He'll pretend that he didn't spend two hours on a dark football field screaming his daughter's name.