I do realize that a 4-8 NU team lost to all 4 yes, 3 on the road, 2 by walk off field goals. We get three of the 4 in Lincoln in 2019. NW lost a 4 year starting qb. Iowa loses both starting D ends and an all everything safety, plus two all conference TEs. Wisconsin slipped on D, then lost their top LBs and will probably start a freshman at QB. Purdue also lost their longtime QB. Minny might be the actual most improved team.
Year two should be a positive step for the defense simply from experience. Nose tackle is much better off this year than last, and I think LB is too. CB is the same, safety is a question but no one in the west slings it around a ton. They also played from behind all year last year. If this offense gets early some leads instead, that changes the outlook for the defense in that game.
Combine all that with another offseason of learning for Martinez and things set up very well for Nebraska in the west.