When the Eagles have the ball

The biggest question about the Eagles offense on Sunday is how the running back playing time will be distributed. Ryan Mathews is probable and could return after missing three games because of a concussion, so the Eagles have another player to join the combination of Darren Sproles, Kenjon Barner, and DeMarco Murray. Murray led the team in snaps in every game he played before last week. Coach Chip Kelly said the decrease vs. New England was because of the matchup, and that explanation will be put to the test on Sunday. The Eagles will either feed Murray against Buffalo and prove it was a one-week anomaly, or they will show that Murray has been pushed down the depth chart. The Bills have the NFL's 19th-ranked rushing defense, with 104 yards allowed per game. They will miss linebacker Nigel Bradham on Sunday, but middle linebacker Preston Brown is tough against the run. Defensive tackle Marcell Dareus is one of the best in the NFL and presents a tough matchup for the Eagles' interior line.

The Eagles passing game is better with Sam Bradford behind center. He has gone three games without an interception, and his two touchdowns last week came on key third-down throws. The Eagles are 5-2 in the last seven games Bradford finished. Bradford must continue taking care of the ball because the offense is not a big-play unit. Bradford needs more from his outside receivers - his touchdowns last week went to slot receiver Jordan Matthews and tight end Zach Ertz, who are his top targets. With top cornerback Stephon Gilmore out of the lineup, the Bills won't have as imposing of a secondary. They are allowing 255.7 passing yards per game. Could this be the week Nelson Agholor finally validates his first-round selection? Look for Matthews to be a prime target with a 7-inch height advantage on Bills nickel cornerback Nickell Robey, although the receiver is listed as questionable with a back injury.

The Bills have only 18 sacks. They led the NFL with 54 sacks last year. Even though the pass rushers have not been as productive, they're still a challenge. Dareus, Mario Williams, and Jerry Hughes can all cause headaches for the Eagles offensive line. However, the line held up well against New England last week. The Eagles are 4-1 this season when their starting five linemen play every snap, and they're 3-0 when left tackle Jason Peters lasts the whole game.

When the Bills have the ball

The key for the Eagles defense against the Bills is stopping running back LeSean McCoy. He has eclipsed 100 yards in three of the last five games - all wins. Expect Bills offensive coordinator Greg Roman to feed McCoy in McCoy's first game against his former team. The Eagles allow 124.7 rushing yards per game, although that number is skewed by Tampa Bay's 283-yard performance on Nov. 22. That was the Eagles' last home game, and they'll need a better showing against McCoy. It helps that Cedric Thornton returns to the lineup after missing last week's game. Linebacker DeMeco Ryans will likely see more playing time if the Eagles use more base defense after spending most of last week in sub packages. McCoy is adept at making players miss. He could see more red-zone action with Karlos Williams absent.

Bills quarterback Tyrod Taylor is also a threat to run. Taylor has 318 rushing yards, and five games with at least 40 yards. But Taylor has been a bigger factor in the passing game. He has 17 touchdowns and four interceptions and has gone six games without throwing the ball to the opponent. In the last two games, Taylor has 502 yards and six touchdowns. Three of those touchdowns went to Sammy Watkins, a top-five pick in 2013 who is emerging into one of the top young receivers in the NFL. Watkins is a big-play threat who averages 18.7 yards per catch and topped 100 receiving yards in each of the last two games. Watkins will be a difficult matchup for Eagles cornerback Byron Maxwell. Rookie Eric Rowe is making his second start at the other cornerback spot.

The Bills also count on tight end Charles Clay, who has 50 catches for 519 yards this season. He will be covered at times by Kiko Alonso, the former Bills linebacker the Eagles acquired for McCoy.

Defensive end Fletcher Cox dominated the line of scrimmage last week, and he will have an intriguing matchup against Bills lineman Richie Incognito on Sunday. The Eagles need edge pressure like they had against the Patriots, when both Connor Barwin and Brandon Graham recorded two sacks.

The Eagles special teams excelled last week, and those non-offensive touchdowns can help a team that struggles to score points. The Bills have not allowed a touchdown in the return game this season, although they've sacrificed points on extra points - kicker Dan Carpenter has missed four this season.

Big number

3.5: DeMarco Murray has averaged 3.5 yards per carry this season. That is the lowest average of any player with at least 150 carries this season. It's fewer yards per carry than any of his teammates. Ryan Mathews averages 5.7 yards per carry, Darren Sproles averages 3.8 yards, and Kenjon Barner averages 4.6 yards. In LeSean McCoy's two seasons in Chip Kelly's offense, he averaged 4.7 yards per carry. Kelly said Murray's reduced role last week vs. New England was not related to production, but it's easy to see that Murray has been the Eagles' least productive rusher this season.

The bottom line

Zach Berman: Bills 24, Eagles 23

Jeff McLane: Bills 27, Eagles 24