I am pretty sure there is an unwritten rule among Coaches that states the team getting beat makes the first move in clearing his bench. Kindof say "Okay you win, congratulations". At that point the team winning follows suite and clears his bench.
In the Wisconsin game, Coach Ryan kept his starters in the game and even started pressing the last couple of minutes, obviously telling Billy that he was still trying to win. I can't be sure, but this is why I thought Coach did not bring in the freshman late in the game.