The addition of Tremaine Edmunds has me excited about this defense.
The Front 4 is leaps and bounds better than it was last year. You're essentially replacing Dareus/Thornton/Washington with Star Lotulelei. Sure, Dareus had raw talent - but Star's consistency I think means Defensive Tackle will be improved. On the Edge - bringing in Trent Murphy should certainly improve the pass rush. Shaq is in a make-or-break it season. In my view, this season is about a race between Shaq and Eddie to replace Jerry in 2019.
The Secondary is still on point. My only concern is nickle-back and depth.
At linebacker - we've essentially replaced Preston Brown with Tremaine Edmunds. In the long run - that's a major upgrade. Edmunds brings a skill set that is going to punish offenses for years (6'5, 250, 4.5 40). I also think Milano will continue to improve. Lorenzo probably only gets used on obvious passing situations at this point.
Overall - I don't really see a weak area for this defense - other than depth in the secondary.