I'm going to try and play devils advocate here and talk from the Nebraska point of view which I'm not advocating for but I'm between classes and bored so here I go.
1) Riley is a pretty solid coach. He had a winning record at Oregon State in about a decade and a half period which is no small feat. It would be much like having a decade of over .500 ball at Iowa State. Expecting a one to two win improvement over 2015 with a solid coach in his 2nd year in the program isn't unreasonable.
2) Movement towards the mean for both programs compared to their 2015 seasons. The 12-0 season is a bit of an outlier in Iowa football history as is a 5-7 season for Nebraska.
3) Tommy Armstrong could improve. By improve I mean cut down on the turnovers. Nothing suggests he is on his way to completing 60% of his passes, but he did throw interceptions at a higher frequency in 2015 than he did in 2014. He also threw a higher frequency of TD's in 2014 than he did in 2015. Going back to point #1, he'll be in his second year under Mike Riley who has a decent record working with QB's. I don't think it's unreasonable that he improves his interception rate by a percentage point which would cut his interception total by about 25%. That could be worth one additional win at least.
4) A 12-0 Iowa team didn't exactly blow away a 5-7 Nebraska team last year. It's not as if you watched the game and thought to yourself, "wow, one team looks a lot more talented than the other." They looked closer to even. Really what you said to yourself was "wow, one team makes less mistakes than the other." which was a microcosm of both teams 2015 season. Some of that is bad luck and some of that is carelessness. Cleaning up dumb mistakes is much easier to do than making players bigger, faster, stronger. It's not unreasonable to think Nebraska will clean up some of the careless play. If they do that, the difference between them and Iowa isn't very large.
