Over the last few weeks, the Bears' defense has played some really good games and some very bad ones.
Then of course there was the collapse against the Seahawks in the fourth quarter.
What we saw then—and have been seeing a bit over the last month—seems to be a general level of exhaustion. It was most evident at the end of the game this weekend, but has been slowly creeping up over the course of the season.
Losing Brian Urlacher might not be the hardest thing the Bears have to deal with at the end of this season.
Of course, the Bears generally do an excellent job of rotating players in and out on the defensive side of the ball to keep them fresh. It helps when the offense is able to move the ball effectively and allow the defense to catch its' breath.
In games like the win over Minnesota, the defense spent less time on the field. A game like Seattle gave them—physical and much closer in score and play—seemed to have a tiring effect at the end.
The Packers and Lions are the most likely teams to push them defensively. The Vikings will test the front seven with Adrian Peterson, but ultimately the pass game won't stretch the field, making it easier on the defense as a whole.
However, the Packers have the deepest corps of receivers in the NFL and the Lions love to throw the ball to the best receiver in the league.
It's going to be hard to contain them, so the offense has to do its part by both scoring and grinding the clock out.
Still, the Bears are facing a time when every unit is tired—and their situation is exacerbated by key injuries to players such as Urlacher.
The coaching staff will surely do what they can to rest their veterans, but they will still need them on the field as often as possible against these teams.
Losing Urlacher is a blow, but the overall defense needs to gather itself for a very vital final four games.
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