What is interesting is that he had 4 steps and a knee down before going to the ground out of bounds, slightly bobbling the ball but still possessing it at the end of the catch.
Apparently, per the rule, a WR could catch a pass in the far left of the endzone, run all the way to the out of bounds line on the right side of the endzone taking unlimited steps with possession, fall out of bounds with a slight bobble, and it is not a catch.
But, that's the rule. The Badgers played so incredibly bad offensively that they didn't deserve to win the game.