Pivot Player: Bears' Brian Urlacher

Fourth in a series on non-quarterbacks who have disproportionate responsibility for their team's success or failure this season.

Our first three NFC North pivot players have all been unproven youngsters with impressive skills sets who have been (or will be) thrust into significant roles on their respective teams. The fourth and final member of this club is a bit different.

There is little doubt that the performance of left tackle J'Marcus Webb will play a role in how the Chicago Bears fare this season. But for me, there is no player whose swing is more important than that of middle linebacker Brian Urlacher.

As you know, Urlacher needed the entire offseason to recover from a sprained knee he suffered in the 2011 regular-season finale. After five days of training camp, the knee swelled up again and ultimately prompted arthroscopic surgery.

This series of events has generated a public discussion about the football mortality of a 34-year-old who is entering the final year of his contract. Urlacher has vowed to play the season but has acknowledged his knee will never be as healthy as it once was, raising concerns not so much about his availability but his effectiveness as he begins his 14th season.

The Bears' defense collapsed in 2009 when a dislocated wrist sidelined Urlacher for 15 games. Urlacher is just as important to its success in 2012, mostly because the team has no credible alternative if he either can't play or is ineffective. Moving strongside linebacker Nick Roach to the middle wasn't a successful alternative in 2009, and it isn't likely to be three years later, either.

To be clear, the Bears can more than get by with Urlacher playing at 80 percent of his prime effectiveness. They are not, however, in position to absorb a more significant decline from an indispensible player. Not having someone resembling Brian Urlacher on the field could be the difference between a good defense and one that threatens the Bears' playoff chances.

That's not a shot at Roach or the rest of the Bears' key defensive players. It's just an acknowledgment that the success of this defense is based on really good play from the middle linebacker, one whose combination of leadership, coverage skills and tackling ability is mostly unmatched across the league.

Earlier: We classified left tackle Marshall Newhouse, cornerback Chris Cook and running back Mikel Leshoure as the pivot player for the Green Bay Packers, Minnesota Vikings, and Detroit Lions, respectively.