This is one of the things I am most looking forward to - how will Nebraska's defense stand up through the Big 10 season. Will the fact that they spent a lot of time with only 1 true LB in a pass happy league cause any problems in moving to a run heavy smash mouth format for much of the season. I suspect that they will be just fine and end up in the top 3 defensively, but that is certainly one of the things I want to see.
We haven't had any problems against the few smash mouth running teams we've faced (KSU last season). One of my favorite things about our D is the adjustments made by the Pelini's, so offenses that find something that works schematically won't be able to use it repeatedly. I suspect, like most games, it won't be the schemes that get NU, but rather the play of the opposing offensive players. If Iowa's RB just has himself a great game, then NU will struggle to stop him. And that's hard to predict.