This was first posted in the diary section and I thought it only proper to point you over to SB Nation's Seahawks site where one of their contributors has done a might fine breakdown of the Bears defense.
Lance Briggs: Lance Briggs is so good it's astounding how little attention he receives. Fast, strong, heady and equally adept defending the pass as stuffing the run, Briggs is often ignored thanks to Urlacher's high profile. This year, perhaps in preparation for free agency, he further developed the ferocity to force fumbles (4) he first showed last season.
Brian Urlacher: The Cover 2 was developed by coaches Chuck Noll and Bud Carson of the dynastic `70's Pittsburgh Steelers. The original prototype for a MLB in the Cover 2 was HOFer Jack Lambert. He was fast, ferocious and could pick the ball like a DB.
Monte Kiffen, Tony Dungy, Lovie Smith, et al developed the modern day Tampa 2. The major difference between the two was an emphasis in the Tampa 2 on smaller speedier players to rush the passer on the line, and dropping the MLB deep to cover the gap between the split safeties. It wouldn't be surprising if in twenty years people refer to Urlacher as the prototype for MLB in the Tampa 2, but, then, some contemporaries would disagree.
Head on over and check them out and keep an eye out as he plans to write about the other units later.