Ryan Mathews remains out; Peters back at practice

There's a player on the Eagles with a concussion who has not been cleared to play, and his expected absence on Sunday against the Tampa Bay Buccaneers will have a major effect on the offense.

The player is Ryan Mathews.

Although Sam Bradford's concussion captured much of the attention this week, Mathews is also out with a concussion. The Eagles' productive No. 2 running back has not even made an appearance on the sideline during practice, and it does not appear that he will play on Sunday. That puts the onus on DeMarco Murray and Darren Sproles to carry the running game.

But there's a dose of good news about the players blocking in front of them. Left tackle Jason Peters' on-again, off-again relationship with practice continued on Thursday, when he returned to the practice field despite a back injury that has kept him out Wednesday's session - not to mention the last two games. He was listed as limited, but he "took a lot of reps," according to right tackle Lane Johnson.

"Close to normal," Johnson said. "It was good seeing him back out there."

There is so much mystery surrounding Peters' status that even coach Chip Kelly did not know Peters would practice Thursday. Just minutes before practice started, Kelly told reporters that Peters would not practice and is still going through rehab. By the time Kelly arrived at practice, Peters was in uniform, ready to go.

Peters' status wasn't determined until two hours before the game on Sunday. That's when Johnson found out he would need to play left tackle. Johnson expects to play right tackle this week.

However, he likely won't block for Mathews, who averages 5.7 yards per carry and has been the Eagles' most productive running back this season. His absence would give Murray a bigger role - Murray averages 16 carries per game - and it could also mean that Sproles gets more touches after carrying three times last Sunday. Reserve Kenjon Barner would also be in the lineup.

"You still have that tough, big, hard-nosed, physical running back," Kelly said. "The other two running backs are obviously Sprolesy, who is a different type of running back, [and Murray]. We use a different approach when Darren's in the backfield, and then Kenjon Barner would be up and be active on game day."

When Murray is in the game, it's worth watching how he collects the handoffs from Mark Sanchez, who is expected to start in Bradford's place. There was confusion about when Sanchez would hand Murray the ball last Sunday. Sanchez carries out the read element of the zone read more often than Bradford. Sanchez and Murray have been working on their handoffs this week.

"Obviously, not working with each other throughout the course of the year and working with Sam, not necessarily reading it," Murray said of the problem. "Mark coming in more of a runner. We got it fixed this week, so it shouldn't be a problem moving forward."

The Eagles will be challenged by the Tampa Bay rushing defense that allows just 3.6 yards per carry - the third-lowest total in the NFL. The Eagles' rushing offense struggled against the Dolphins' rushing defense last week even though it entered the game as the second-worst unit in the league. So statistics can be deceiving in both directions. The success of the running game often comes down to the effectiveness of the offensive line and not the quality of defense the Eagles face.

"It's so hard to play 11 against 1," Johnson said. "If one guy doesn't do their job, our offense really can't run."

The Bucs defense is led by defensive tackle Gerald McCoy, one of the best defensive linemen in the NFL, and linebacker Lavonte David, who is consistently one of the league's top tacklers. Murray mentioned them both when sizing up what to expect on Sunday.

How the Eagles run the ball could dictate the result on Sunday. The Eagles average 159.8 rushing yards per game in wins but only 83.4 in losses. They'll likely need to do it on Sunday without Mathews for the first time this season, although they could have Peters back in the lineup.

zberman@phillynews.com

@ZBerm