To be fair, he is having a subpar season statistically. He is on pace the finish with just over 60 tackles after averaging over 100 tackles between 2007-2009 (although he did miss two games with an ankle injury).
Also, at 31 years old, Cooper's best days are behind him. He no longer has the same pop at the point of attack, which is a big reason the Chargers picked Donald Butler in the third round of this year's draft (Butler is on injured-reserve with an Achilles injury).
LB Stephen Cooper
As the quarterback of San Diego's defense, Cooper's responsibilities in Indianapolis will be enormous. He must decipher Manning's audibles and gesticulations, real and phony, and be sure the Chargers defense reacts appropriately.
It's a task that often proves too much for even the best of defensive leaders, but not Cooper.
Since 2007, Cooper has started four games against the Colts. The Chargers won three of those games, with Cooper averaging better than 10 tackles in those victories. The Colts have been held under 25 points in each of those contests, due in large part to Cooper's ability to put his teammates in position to succeed.
There is no overstating the importance of Sunday's game. If the Chargers win, they will be above .500 with a very manageable schedule the rest of the way (the Raiders and Chiefs at home, followed by three games against opponents with a combined record of 8-22).
If the Chargers lose, they risk falling two games behind Kansas City with five games to go. Given the Chiefs' equally soft schedule, that may be too much to overcome.
This Thanksgiving, while you're sitting around the table talking about how dominant the Chargers defense would be if it had an upgrade over Cooper, just remember how vital a role he will play in the biggest game of the season.
And be glad that -- although Cooper is no Ray Lewis -- he is hardly a turkey.
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Michael Lombardo is a member of the Pro Football Writers of America and a long-time contributor to the Scout.com network. His analysis has been published by the NFL Network, Fox Sports and MySpace Sports. He has followed the Chargers for more than 15 years and covered the team since 2003. You can see more of his updates by following him on twitter.