This has to be based mostly on the fact they have had two top 25 recruiting classes in a row. And as Twins noted, a lot of teams in the Big 10 west will take a step back this year. Wisconsin, Purdue and Northwestern will have inexperienced QBs. Illinois and Minnesota, meh. So it should be between Iowa and Nebraska. Actually Nebraska has a fairly realistic shot at 10-2. On the local radio here in Omaha they are talking 11-1 even.
I think Frost is a good coach and he'll probably do well in Lincoln. However, I don't think they'll win 10 games. Maybe 8.