PHILADELPHIA — The Eagles turned in their worst offensive performance of the Chip Kelly era in being held to 139 yards and nine first downs by the Seattle Seahawks in a 24-14 loss in Week 14.

Quarterback Mark Sanchez completed just 10 of 20 passes for 96 yards. Not one of those 20 attempts was thrown in the direction of running back Darren Sproles.

Sproles is considered one of the best pass-catching backs in the NFL. He caught 232 passes for 1,981 yards and 16 touchdowns over the past three years for the New Orleans Saints before being traded last March to the Eagles.

When the trade was made, Eagles fans’ tongues were wagging at the thought of Sproles in Kelly’s offense.

But 13 games into his first season in Philadelphia, the 31-year-old Sproles has just 29 catches. Yes, he leads the league in punt returns (14.1-yard average). Yes, he’s averaging 6.1 yards per carry and has five rushing touchdowns on those infrequent occasions (49 rushing attempts) when he spells LeSean McCoy.

But Sproles was expected to make his biggest impact as a receiver out of the backfield.

So far, that hasn’t happened.

“We’re trying (to get him the ball),” said Kelly, whose 9-4 Eagles can take command of the NFC East Sunday night when they face the 9-4 Dallas Cowboys for the second time in three weeks.

“But a lot of times, they’re doing some different things (to prevent that). The Seahawks dropped (safety) Earl Thomas down a few times to kind of double Darren. When you see a guy who has the impact he had in the first couple of games, we’re starting to see a lot of different coverages on him in terms of what we’re trying to do, as far as bringing him out of the backfield and things like that. We’ve seen some different looks, and rightly so because of the type of player he is.”

Sproles had 14 receptions for 196 yards through the first three games, including a seven-catch, 152-yard performance in the Eagles’ Week 2 win over Indianapolis. Since then: 15 catches, 117 yards.

Last season, the Eagles faced more man-to-man coverage than just about any team in the league. One of the reasons Kelly was interested in Sproles was because of the difficulty in covering and tackling him in space.

At the very least, he would force teams to play more zone against the Eagles. And that’s what has happened. Kelly said that last year, teams played man against the Eagles 60 percent of the time and zone 40 percent. He said so far this year it has been 58 percent zone and 42 percent man.

Sproles said defenses have frequently doubled him or dropped a defensive end out to help on him or slow him down.

“They’re putting two people on me,” he said. “Which means somebody else has to be wide open. So it doesn’t really bother me too much. It’s been good, but it could be better.”

Kelly hasn’t been keen on the idea of putting Sproles and McCoy on the field at the same time (they’ve lined up together just 24 times). Which is a big reason why Sproles, who averaged 30 snaps a game the last three years with the Saints, is averaging just 21 a game this season with the Eagles.

“We’ve got him out there,” offensive coordinator Pat Shurmur said. “There are times when we intend to give him the ball and can’t for some reason.

“The other team is obviously well aware when he’s on the field too. If he’s doubled or for some reason covered, you move on (to another receiver). But we continue to have plays for him.”

SERIES HISTORY: 112th meeting. Cowboys lead the series, 62-49. The two teams played in Dallas on Thanksgiving, with the Eagles winning, 33-10. LeSean McCoy had a season-high 159 rushing yards in that victory.

NOTES: QB Nick Foles will miss his sixth straight game Sunday as he heals from a fractured collarbone. He has been throwing the ball and is scheduled to be examined by a doctor early next week. But the earliest he probably would be activated is Week 17. … PK Cody Parkey was limited in practice Wednesday with a groin injury. Parkey has kicked with the injury the last two weeks, and it has affected the distance on his kickoffs. … RB Chris Polk was a limited practice participant Wednesday with an ankle injury. He played last week, but did not have any touches. … WR Josh Huff practiced fully Wednesday. He injured his hip in Sunday’s loss to Seattle, but is expected to play this week. He returned kickoffs against the Seahawks. … LB Emmanuel Acho is expected to get expanded playing time this week. He still is on the injury report with a groin injury that forced him to miss the first Dallas game on Thanksgiving. He played just two snaps last week against Seattle.