Let's assume Iowa's opponents, on balance, have been average. Let's also suppose that a top-10 team will beat an "average" team 80% of the time. The odds of that team winning 12 straight are less than 7%. Even if you expect to beat an average team 85% of the time, the odds of finishing 12-0 are only about 15%.
It would seem that either Iowa has completely defied the odds, or they are really, really good.
It would seem that either Iowa has completely defied the odds, or they are really, really good.