The thing is, Urlacher at this point was pretty much expendable as a player.
You'll say "But the Bears don't have anybody playing linebacker this season!" (Prior to the DJ Williams signing, of course.) And I would have said you were right - the Bears lost Nick Roach to the Raiders and without Urlacher, the Bears may have needed two starting linebackers. Except for two things. Actually, seven.
I'm going to give you a quick list of names: Julius Peppers. Henry Melton. Charles Tillman. Lance Briggs. Tim Jennings. Five guys that all are better and more productive players than current Urlacher. It's not like the defense is returning no one, or suddenly getting back an "in his prime" Urlacher.
The added benefit of not paying Urlacher extra is being able to pay other players. DJ Williams signed for 1.75 million. If Urlacher had gotten the deal Sean Jensen reported he wanted (about 2 million with a chance to earn 1.75 in incentives, depending on the ease of those incentives), the Bears could have been on the hook for 3.75 - a full two million over that. Instead, the Bears get Williams for less than half that as well as retain cap room to make another play, instead of locking it into one player that may not have much left, if anything.
And I'm not going to lose sleep over the loss of leadership and the ability to know/call the plays. Systems are one thing, but vary from coordinator to coordinator - and even though Mel Tucker said he'll use the same terminology, how he'll run the defense could be a different matter.
So relax - not signing Urlacher doesn't mean the defense will suddenly be miserably bad.