Here are some potential X factors in this weekend's games:
Buffalo Bills (5-4)
Opponent: Miami Dolphins (2-7)
X factor: LB Nick Barnett
Analysis: Buffalo's defense was embarrassed last week in a 44-7 trouncing by the Dallas Cowboys. It was the most points the Bills allowed all season. But the mentally tough teams can overcome these kinds of clunkers. That is where Barnett comes in. The veteran free agent from the Green Bay Packers has done a solid job providing leadership in Buffalo. His leadership is needed now more than ever with the Bills falling out of the playoff race. Barnett needs to have a good game to set the tone for Buffalo's defense on the road in Miami.
Miami Dolphins (2-7)
X factor: CB Vontae Davis
Analysis: Good cornerback play always is important when playing Buffalo's spread offense. The New York Jets and Dallas Cowboys had great secondary play against the Bills. Miami will try to do the same. Davis has had his issues with the team this season. He's been in and out of the lineup with a hamstring injury and was suspended one game for reportedly getting into a scuffle at practice with receiver Brandon Marshall. But the Dolphins need Davis to be on his game. The Bills like to throw the football, and there will be plenty of opportunities for Davis and Miami's secondary to make big plays to impact the game.
New England Patriots (6-3)
Opponent: Kansas City Chiefs (4-5)
X factor: DT Vince Wilfork
Analysis: Kansas City will be huge underdogs Monday night at Gillette Stadium without starting quarterback Matt Cassel (hand). Essentially the Chiefs' only chance to pull the upset is by running the football, which happens to be the best asset of New England's defense. Wilfork has been steady force for the Patriots in the middle. He has 25 tackles, 1.5 sacks and, surprisingly, two interceptions. New England is ninth in the NFL in run defense in large part because Wilfork is hard to move. With Chiefs backup Tyler Palko at quarterback, this game is tailor made for New England's defense to hide its weakness (pass defense) and play to its strength (run defense).