I'm an outsider but I think Nebraska changed a lot in that it had a system of old style option football that worked then decided to abandon it after a 10-3 season capped by a bowl win in 2003. That system, to me, made Nebraska what it was. I live in SEC country and I can remember people in SEC country saying that system was obsolete before Nebraska clubbed Florida in the de facto 1995/1996 national championship game. Short memories apparently prevailed as I can remember SEC fans saying the same kind of thing before Nebraska clubbed Tennessee in the 1998 Orange Bowl.
Yes they went a few years without a national title after 1997/1998 but they were in the BCS championship game at the end of the 2001/2002 season. Yes they lost the Big 12 title game that year but when you lose a game by 62-36 the problem obviously isn't the offensive system.
I think the system Nebraska had is what made Nebraska great. During all of its glory years Nebraska wasn't ever near the top in terms of NFL talent production overall. But they didn't need to be on the offensive side. They were using a different kind of player. Tommy Frazier, for instance, was never a threat to be a NFL quarterback. But he was great for what Nebraska did and the fact that he wasn't an NFL type quarterback didn't help Florida's outstanding 1995/1996 team any.
I just think Nebraska made a mistake a few years back. I don't think there's any doubt that their program went down instead of up after they decided to change their basic approach. It's been pretty good at times. But it's not the same as it was before.