I understand they have a fairly favorable schedule and all that. However, Wisconsin's offense was fairly "meh" last year (89th in Total Offense and 67th in Scoring Offense), so the fact that they have returning starters on that side of the ball isn't exactly a reason to be thinking of them as world beaters or anything. At least statistically, Bart Huston, who was a senior last year, was the better QB, Alex Hornibrook was good, but not outstanding or anything like that. They are also a more run oriented team (104th in Passing Offense vs 39th in Rushing Offense) and lost their top two rushers from last year. Their defense is really what carried them, and I know they have a lot returning on that side, but they will have a new DC. It may not have much of an effect, but you never know.
All of that is say, I understand they have a lot returning, and have a fairly favorable schedule. Their cross-division games are against Indiana, Maryland and Michigan. Not quite the easiest 3 they could get, but pretty close. Still, they do have to play Nebraska on the road, which won't be a gimme. A lot of people also seem to forget about them barely squeaking by Georgia State last year, a team that was winless at the time, and finished 3-9 with those 3 wins coming against an FCS school and two Sun Belt schools that, like them, had only recently moved up from FCS. Georgia State lead that game in the 4th quarter, and Wisconsin never completely put them away. If they play a game like that one against, say, BYU on the road, they could very easily lose.
So, while it certainly isn't completely outside the realm of possibility they would go 12-0, it isn't exactly likely either. Lots of teams, including ones more talented than Wisconsin, have slipped up at some point in recent years, so it easily could happen to them.
