From the magazine:
TEAMS ON THE DECLINE
NEBRASKA
The Cornhuskers were on last year's "likely to improve" list, but really, only the win total improved. Nebraska actually fell from 36th in S&P+ in 2015 to 46th last fall. What changed? Luck and close-game performance. Based on national averages for fumble recoveries and the ratio of interceptions to passes broken up, Nebraska's turnover margin should have been about plus-0.5 in 2015 and minus-4.8 in 2016; instead, it was minus-12 in 2015 and plus-5 last year. This drastic shift in turnover luck put its finger on the scales. The Huskers were 3-6 in one-possession games in 2015 and 3-1 in 2016. Otherwise, the were, at best, basically the same team. That's not necessarily encouraging considering Nebraska now returns only 12 starters, third fewest in the Big Ten.
Since the end of 2016, we have upgraded to a top-flight defensive coordinator (and are paying him handsomely), switched to a defense that better fits our bevy of linebackers, and also picked up Donte Williams, who has been recruiting like a madman since he arrived. Not to mention we now have a QB that not only fits Riley's system, but also had a year to redshirt and develop chemistry with teammates like JD Spielman.
That doesn't sound like a team on the decline to me.
That sounds like a team making moves to get better.