Casey Matthews will be tested by Cowboys running game

Last season, in the Eagles' season finale against the Cowboys, Casey Matthews did not play a single snap on defense. He had been moved from inside to outside linebacker before the season but played sparingly throughout the year. By the final game, which decided the NFC East crown, Matthews was only on special teams.

A year later, circumstances have changed considerably. Not only is Matthews back inside, but he will start against the Cowboys on Thursday in the Eagles' biggest game this season to date, and he will likely play every snap at the "Mike" linebacker spot.

A series of injuries has thrust Matthews back into a role he was forced into as a rookie and later relinquished, and now he faces his most difficult test. The Cowboys have the NFL's second-ranked rushing offense and DeMarco Murray has rushed for a league-high 1,354 yards.

"It all starts with that run," Matthews said this week. "If they get success running the ball, it opens up their passing game. If you shut it down early, get a little lead, get a cushion, it narrows down their offense."

It is easier said than done. Murray has eclipsed 100 yards rushing in 10 of 11 games and has yet to be held under 4 yards a carry in a game. He runs behind arguably the best offensive line in the league - a unit that has jelled under noted line coach Bill Callahan.

The Eagles counter with one of the NFL's better run-stopping lines, but the primary challenge for coordinator Bill Davis' rushing defense will come at the second level. When DeMeco Ryans suffered a season-ending Achilles tendon rupture four games ago, the Eagles lamented the loss because of his leadership and adeptness at calling the signals and setting the front.

A big drop-off because of his absence hasn't been discernible, but that could change in Texas. Ryans was an above-average run defender. Matthews has been passable, as has been Emmanuel Acho, who has split the "Mike" snaps. But Acho is questionable with a groin injury.

It will be Matthews most of the time opposite Mychal Kendricks at inside linebacker. Eagles coach Chip Kelly said he is confident in the former Oregon player.

"I think Casey is just kind of a steady Eddie in there: can get the front set, does a real good job on first and second down," Kelly said. "When we get to dime, he comes out, but I think Casey has been consistent while he's been playing for us."

Davis has increasingly used his dime personnel (six defensive backs) rather than his nickel (five) on expected passing downs. Kendricks has stayed on the field, but Matthews or Acho have come off for cornerback Nolan Carroll. The smaller unit has left the Eagles susceptible to the run on third down.

The Cowboys can pass and run effectively out of both their "11" (three wide receivers) and "12" (two tight ends) sets. If they go "11," the Eagles will likely employ either their nickel or dime package. If they use their "12," Davis will be able to stay in his base defense on run downs.

The Eagles' base defense has held offenses to 3.4 yards per carry. With their nickel and dime personnel, they have allowed an average of 5.8 yards, although the numbers are certainly skewed by the element of surprise when a team runs on passing downs.

Davis' base unit has done a better job against the run over the last six games, in particular after the Eagles surrendered 218 yards to the 49ers in Week 4. Over the first five games, the Eagles allowed 4.2 yards a rush; over the last six they've surrendered 3.6.

"It's tough to run inside on us," Davis said. "The San Francisco game we had issues on the edge, but we really have kind of cleaned that up, and that'll be challenged this week because they are an edge rushing team."

The Cowboys' bread-and-butter is their stretch run play in which the line pulls one way and Murray runs outside with, ideally, several lane options. The Eagles limited the Redskins and Cardinals' stretch runs earlier this season.

But the Cowboys have mastered it, with athletic linemen such as tackle Tyron Smith and rookie guard Zach Martin effectively blocking linebackers in space. Gap discipline is of the utmost importance in defending it.

"The stretch is their No. 1 play, but they've got counters, so we've got to have our eyes right this week," Matthews said. "DeMarco - when he gets in the open field, he's able to hit the hole when he's at his best. If you can get him to stop his feet and change direction, I think that's where you can shut him down."

If the Eagles can slow the run on first and second down, they can force the balanced Cowboys to throw on second and third and long. There is no guarantee that they will stop quarterback Tony Romo and his bevy of receivers, but it will get Matthews, who has struggled in coverage, off the field.

If Acho is sidelined, rookie Marcus Smith will be the first inside linebacker off the bench. The Eagles' top draft pick hasn't been able to crack the lineup, but Davis said, ready or not, Smith will be the next up.

"He'll make some mistakes and he'll make some plays," Davis said. "We're OK with that."

@Jeff_McLane