Because they didn't really improve. They added Raji, Matthews, and Anthony Smith, but two of those guys are rookies that are pretty boom or bust (I didn't like either of them going into the draft, and the other just isn't really all that good). They are a young team that is getting more experienced, for the most part, but their best corps is getting older with Harris and Woodson.
The defense as a whole wasn't impressive last year, and any time there is a change of schemes I tend to expect regression for the first year or two as opposed to instant improvement. We've been down this Kampman road before, but I still say that he was the team's best defensive player last year and now how he is somewhat of unknown. Forgive my sarcasm, but just like I don't expect the defense to magically get better in its transition, I don't expect AK to magically get better in his transition, either.
To kill the suspense, no I'm not a Packer fan. I'm a Viking fan who loves to chat sports. But I'm also level-headed, I give credit where it is due, and try to look at things like this from an analytical persepective instead of a fan's perspective. Discussion is generally more fruitful when everyone isn't looking at things from green or purple tinted glasses.