Their defense looks much better this season. Last season Urlacher was banged up, he looks tough this season. They've added 1st rounder Shea McClellin who looks pretty nasty, and Stephen Paea, a 2nd rounder from last year, has really emerged as a playmaker. Along with the dominant playmaker that is Julius Peppers (sound familiar?).
They are the #1 defense as far as points per game (the only stat that really matters). #1, giving up 13 points a game. And now facing a struggling offense.