Hobbled Offensive Line Is Foles, Kelly and Eagles' Achilles' Heel

"It all starts on the offensive line."

Everyone who played the Madden video game series when John Madden was still in it heard him intone that old chestnut often enough to be the soundtrack of their nightmares.

For Philadelphia Eagles head coach Chip Kelly's innovative offense, that's more than an old-school football cliche—it's an absolute truth. His read-option offense is built on getting a numbers advantage in the box and winning the battle in the trenches.

"We want to get off the ball and be a physical, downhill-running team," Kelly told a coaches' conference in 2009, via Charles Fischer of FishDuck.com. "We want to come off the ball, create a double-team, knock the crap out of the defender and deposit him in the linebacker's lap."

Instead, his patchwork offensive line was dominated by a 49ers front seven missing quite a few pieces of its own. As a result, an Eagles offense that looked like it could overcome any adversity was completely ineffective, even with a historically great assist from the other two phases of the game:

Quarterback Nick Foles, just a week removed from an emphatic return to form, looked timid and shell-shocked. Running backs LeSean McCoy and Darren Sproles were again bottled up on the ground. The NFL's second-highest scoring offense, per Pro Football Reference, was completely shut out in Santa Clara.

The Eagles, following a 26-21 loss to the 49ers on Sunday Night Football, have fallen back into the NFC East pack. With the New York Giants and Dallas Cowboys trending up, how long will it be until the Eagles are the Eagles again? Will it be this season?

The M.A.S.H. Unit

It wasn't a surprise the Eagles played with a reshuffled offensive line.

Reigning first-team All-Pro guard Evan Mathis is on the injured reserve/designated to return list with a severe MCL sprain. 2013 No. 4 overall pick Lane Johnson is serving a PED suspension, and his replacement, Allen Barbre, suffered a season-ending high-ankle sprain in Week 1. Starting center Jason Kelce has a sports hernia that required surgery.

Three weeks after the season opener, only left tackle Jason Peters was left to start against the 49ers in his original position, according to Zach Berman of The Philadelphia Inquirer. Eagles coach Chip Kelly told the media earlier in the week that he believed the reserve offensive linemen were capable of getting the job done:

"

We feel confident in our guys...We felt our second offensive line did a very good job in the preseason. When they had an opportunity to get in there, we think the style that they train—our guys get a lot of reps in our training sessions—gives them an opportunity.

"

After the game, Kelly sang a different song, per Reuben Frank of CSNPhilly.com:

Instead of a downhill running game snowplowing through the defense, McCoy and Sproles were stuffed at the line, as the 49ers front seven strung out running plays along the line of scrimmage and frustrated the two backs time and again. They ran just 11 times for a wretched 1.9 yards per carry, per NFL.com—even worse than last week's 2.0 average on 21 carries.

Unlike last week against the Washington Redskins, though, Foles and the passing game couldn't begin to make up for it.

The Charity Case

After winding back the clock to 2013 in Week 3, Foles regressed to, well, worse than he's ever been.

He completed just 48.8 percent of his 43 pass attempts and averaged just 4.53 yards per attempt. He threw two interceptions. To make matters worse, receiver Riley Cooper and tight end Zach Ertz both lost fumbles that ended two other Eagles drives.

When the Eagles managed to hang on to the football, they couldn't do anything with it. They had just 11 first downs all game and were just 5-of-13 on third downs. They were penalized 10 times for 70 yards and averaged just net 3.8 yards gained on 56 offensive plays.

As Jimmy Kempski, Eagles writer for Philly.com, pointed out on Twitter, Foles and the Eagles didn't even make it to the 49ers side of the field until just four minutes and 36 seconds were left in the game. That's unthinkable for an offense that came into the game averaging 33.7 points, per Pro-Football-Reference.com.

For once, Foles and the offense got plenty of help from the other two phases of the game.

Not only did the Eagles block a punt and recover it in the end zone, and not only did Sproles rip off another return touchdown, but the defense got in on the act as well. For the third time in four games, safety Malcolm Jenkins snagged an interception—and this time, he took it to the house.

Jenkins has been one of the best free-agent signings in the NFL this season, especially for the money the Eagles paid. At the quarter mark, his three picks are the most by an Eagles safety since Kurt Coleman's four in 2011. For the Eagles, adding that ball-hawking dimension to the back of the defense is huge, both in scaring opposing offensive coordinators and supporting Foles.

All Foles and the offense needed to do was put together one drive and score one touchdown. In the game's dying minutes, it looked like they were going to do it.

On 3rd-and-14 from the 49ers 39-yard line, Foles found Maclin, who made an unreal one-handed diving grab along the sideline for a first down. Then, he hit rookie Jordan Matthews for a critical first down. McCoy tacked on his longest run of the game: a five-yard carry that put the Eagles one yard short of the most improbable win yet in a season that's been composed of nothing but improbable wins.

Then, this happened:

On 4th-and-goal, Foles, slightly gimpy from taking an angry Justin Smith to his back earlier, couldn't get far enough away from the pass rush to set his feet and deliver an accurate ball to Maclin. His potential game-winning pass sailed out of the back of the end zone, and the Niners took over.

The Emergency Room

At the time of this writing, searching Twitter for "Foles play call" revealed an awful lot of angry Eagles fans criticizing Kelly for trusting Foles' legs and arms instead of McCoy. The fourth-down call, though, revealed that Kelly could see exactly what we'd been seeing all game long: His offensive line couldn't block the 49ers for love or money.

With the game on the line, Kelly's offense couldn't do what Kelly's offense was built to do. That's a big, big problem.

Johnson will return from suspension next week, and that should help two positions: Johnson will resume his role as the starting right tackle, and Todd Herremans will slide inside to his usual right guard spot. That should make a noticeable difference.

Until Mathis and/or Kelce return from their longer-term injuries, though, Foles is going to have to dig deep and play with the confidence and aggressiveness he showed against Washington—even when nothing's breaking his way.