Green Bay run defense last year overall: 119.9 yards per game allowed
But when you break it down a little bit:
Green Bay run defense, first 8 games: 153.3 yards per game allowed (dead last over that period, obviously)
Green Bay run defense, final 8 games: 86.4 yards per game allowed (No. 6 rush defense in the league the last 8 games)
When they moved Clay Matthews to the middle on traditional run downs, you saw how much that helped them, but it's true - they're taking their OLB and one of their best pass rushers and moving him away from the spot where he, as an individual, is perceived to have the most value. Yet, if moving him from the outside to the middle injected that much life into the team's run defense, I'd say his contributions and value may be greater than we had thought all along. Certainly a far distance from 'just a pass rusher', even though you can't have enough of those. They rid themselves of A.J. Hawk, Jamari Lattimore and Brad Jones this offseason too - addition by subtraction - and then added Jake Ryan in the fourth (thought they would take one earlier) whose getting some first-team reps, and then finally, they get B.J. Raji back, who is in a big 'prove it' year.
Pass defense finished 10th in the NFL, seventh in interceptions. Tramon Williams and Davon House gone, though, so we'll see. Without House, the defensive backfield lacks height. Although they drafted two secondary players in rounds one and two, Sam Shields still there of course, and so long as Micah Hyde/Casey Hayward both stay healthy and exhibit some sort of an upward trajectory then that shouldn't fall off that much. You could do a lot worse than Ha Ha Clinton-Dix and Morgan Burnett as a safety tandem.
The Packers special teams royally sucked last season but that stuff can change drastically from one year to the next - don't think the Packers have A TON of holes like some will say.