UCF had no real prior culture to overcome, even though they were not winning. I think there is a lot of talent down here in Florida, you can find players all over the place, and no culture to fight against..
At Nebraska, there isn't talent anywhere, and you have this huge "Big Red Fanbase" that says you gotta do it this way and that and whatever.. this goes to the administration too, it's just an inbred culture that still lives at Nebraska, no matter who is the coach.
So you got talent issues, culture issues, entitlement issues, and now a different conference to contend with too. That's part of it as well.