Pretty much this. I was disappointed MN didn't go for it as well, but that wasn't the difference. The D played well early in the game, and with the weather there was reason to believe this would be a really low scoring game (and in fact, it was only 10-7 at the half). Field position matters in a game like that, so the staff took a calculated risk. Probably wrong, yes, but if you get stuffed there on 4th would we see this outrage? The way MN ran the ball early, there was a good shot it gets stuffed.
Wisconsin had a great gameplan. They schemed up 4 or 5 wrinkles on O to get matchups and EVERY SINGLE ONE of them worked to perfection. They schemed up a D to get pressure up the middle while pressing our WRs and it worked 85% of the time and really rattled Morgan. Pretty much the worst game imaginable. Sucks.