The leading tackler at linebacker and the leading tackler on the DL need to be replaced. In order of finish in total tackles, 1, 7, 8 and 9 leave. Stille has starter's experience and has played in some fashion since his RS frosh year. I would thing Deontre and Damion will be the other starters Not much in terms of proven depth, but certainly I'd think NU will get something out of Green, Ty, Rogers and/or Wildeman. Honas and Miller will at least start out in the middle. There are promising players behind them (Mauga is intriguing), but depth remains a question mark. Tannor, Jojo and Nelson return at OLB. DiCap, Cam (6th leading tackler), Clark, Deontai, and Dismuke (3rd leading tackler) all return. Depth not proven, but promising.
Don't see big improvement on the DL, but if that group could hold serve in terms of productivity, that would be great. LB play could improve this year. Jackson is gone, but lots of experience remains among the DBs and Deontai returns from injury. In addition, quite a bit of young talent has been added to the roster and Fisher knows what he is doing with these guys.
The defense improves when a QB is worried about getting hit as opposed to waiting for a WR to get open on a 3rd and long. Not sure if that happens this year.