As Coach K put it back in 01, having a high-caliber player like Dahntay to practice with helps your guys deal with tougher competition down the line. Because Dahntay's "games" are essentially the practices for the team, he went all out.
Last week, Nolan pretty much said the same thing about Seth. He has improved so much as a player because he has to deal with Seth's A+ game every time they practice, cuz you know Seth is just dying to get onto the floor for a game.