I don't think Iowa is necessarily more physically dominant than Minnesota. Faster, yes--but not more physically dominant. Game conditions matter. Iowa came out supremely confident, knowing they were going to beat the tar out of their little brother. The Gophers came out feeling like the little brother, feeling the weight of the Ferentz/Fleck history and perhaps knowing that their O game plan would do little to stress or confuse the Iowa D.
When a Gopher team--with its lack of explosive play capability, or even mndset--is down 17-0 two minutes into the second quarter, and it is clear that your simplistic O prep and plans are hopelessly transparent and anticipated at every step by a focused, disciplined Iowa defense, and you know that your afterthought STs are operating at a huge deficit to Iowa's ST commandos, you know the game is both lost and hopelessly out of hand. You should play you hearts out nonetheless, but you know the cause is hopeless and your generals have failed to prepare you adequately for the battle. You lose heart. Call it quitting if you want. I would call it battle shock. You could see it the players body posture and eyes.
I think the Gophers will regroup and win a few more games--games in which PJ doesn't fear the opposing coach, and the opposing coach and players can't feed off that fear. Maybe fear is the wrong word; the issue is more nuanced. But Ferentz has a profound psychological advantage over PJ, and both teams feel it ... more and more each year. It feeds Iowa's strength and saps the Gopher's.
On to the MSU game!