Because they played Alabama, and their SOS makes it look as if they played nobody. Anybody would consider playing Alabama and 2 schools between Troy, Miami of Ohio, and Hawaii tougher than UNI, Iowa, and Toledo yet there's a 100+ difference in SOS which makes no sense.
Playing 3 nobody's is going to make it look that way. ISU would probably be 3-1 with Wisconsin's schedule and they are 1-2 with their schedule so no I don't think anyone would consider Wisconsin's harder.