The lesson came with unexpected force, enough that you might understand if Toby Gerhart didn't remember it. Or, at the very least, had tried to forget it.
But he does remember.
Last summer, at his first NFL training camp practice, he learned the difference between college and the pros.
Practice was in shells -- helmet and shoulder pads. Gerhart ran out of the backfield, caught a screen pass. Enter defensive tackle Pat Williams.
"I turned and he just de-cleated me," Gerhart said after Monday's Vikings practice at Winter Park. He was smiling at the memory. Really. "I was like, 'We're not even in full pads.' It was ... I didn't know what to expect."
Now, he does. And that is making all the difference as Gerhart tries to carve out a larger role as the backup to star running back Adrian Peterson.
A season ago Gerhart came out of Stanford as a second-round draft pick with gaudy numbers and a reputation for being a power runner. For the first weeks of training camp, the veterans made sure he paid his dues. Williams clobbered him early and often, then talked at length about it. This wasn't college anymore, he said. Time to test the college kid. There was a scuffle with defensive end Ray Edwards. At times it looked as if Gerhart had a horn on his helmet and a target on his back.
Gerhart holds no nostalgia for that camp. Nor does he have any lasting bruises, either literal or figurative. But he will tell you that going through it all made him stronger.