Against PSU, I didn't find them to be particularly impressive on D. I think that game was in large part the result of the rain and PSU hurting themselves. Then I look at their defensive stats, and realize that they're still giving up 302 yards/game. For comparison, we're giving up 392 yards/game.
The difference? Well, first of all, we've played ND, who is the #10 offense in terms of yds/game, and MSU, who is #21 in the nation.
On the other hand, Iowa has faced:
Northern Iowa = Not even FBS, but they do average an impressive 480 yds/game
Iowa State = #53
Arizona = #33
Penn St = #41
Arky State = #81
So really, saving 92 yds/game against lesser competition isn't *that* impressive.
Second of all, they've gotten 10 turnovers already. That's two per game, and one of the reasons they've been able to save so many yards. Now, those turn overs may very well have been "earned," but something tells me that their opponents may not have been so careful with the ball.
I guess what I'm saying is that we should be able to gain some yards on them as long as we hold onto the ball.