The problem for Nebraska is that the home state doesn't produce any talent, like none, because very few people live there: it ranks just ahead of Idaho and just behind New Mexico, in population, and schools in those states aren't competing for Natty's anytime soon. To compare it to Wisconsin, Wisconsin has three times the people of Nebraska and produces an average of 5 to 10 D1 football players a year, and Wisconsin almost always lands all of them. Nebraska often produces none. So, Nebraska starts off in a hole each recruiting cycle.
With no instate talent, they have to compete with everyone else in Texas, California, Florida and everywhere else for players. In the 90s, Nebraska had superior facilities (the Huskers were way ahead of the game in weight training.... and juicing) and a current record of Nattys which allowed them to land talent comparable to other elite programs. Now, everyone has elite facilities. If you are a solid player from Texas and either didn't get recruited by the Longhorns or didn't want to go there, Nebraska was an attractive option. These days, TCU, Texas Tech, OK State and dozens of other schools are more attractive options.... Heck, such a player may even want to go to Wake Forest over Nebraska. That was never the case. There are just a lot more schools in the mix for top-end recruits willing to leave their home area than ever before and Nebraska is just one of them and behind many if not most of them; why would anyone want to spend 4 years in the desolate prairie of Lincoln Nebraska? For the same reason that not many people choose to live in Nebraska, there aren't that many people that want to go to college in Nebraska.
With a great coach if Nebraska goes the developmental route, they can be a 7-8 win team as a ceiling, but the days are forever gone when Nebraska is annual top 10 program.