Run left? Nope. Run right? Not happening. Run middle? No chance. The Kansas City Chiefs’ defense has stymied running games through two weeks, holding the Jacksonville Jaguars and Dallas Cowboys to a total of 108 yards and zero touchdowns. Now headed into Week 3, they face their toughest test yet: Chip Kelly and the fast-moving Philadelphia Eagles.

Kelly’s offense runs the ball with great effectiveness, piling up more than 360 yards rushing through two games. There are several reasons for this, most notably their neck-breaking pace and exceptional coaching.

They don’t huddle and are always looking to keep the ball moving, which explains why they were able to run 53 (!) plays in the first half of a Week 1 while demolishing the rivaled Washington Redskins. They didn’t have the same success in Week 2 against the San Diego Chargers, but did still run for more than five yards a pop.

To run through defenses with such ease, the running backs and offensive line must be in sync. The Eagles have been just that, as their blockers have moved in cohesion while creating bulldozer-sized alleys with their zone blocking, making running back LeSean McCoy’s stretch runs that much more effective.

But now they run into the Chiefs. Their defense features a daunting front seven, and has bottled up running backs. It’s given up 2.8 yards per carry and six first downs, good for fourth fewest in the NFL. It’s also made blockers’ lives a living hell because of how strong, athletic, and aggressive it is.

The Chiefs don’t sit back and wait for the running back to come them. No, they come after the running back and make damn sure that he’s not invading their territory, which they’ve marked at the line of scrimmage.

Their front three is led by breakout superstar nose tackle Dontari Poe. A year after being selected  No. 11 overall in the 2012 draft, Poe has taken the next step to becoming a dominant nose tackle. He’s become better with his technique, thus better at handling the same combination blocks the Eagles’ linemen use, and is now quicker since he’s reportedly lost between 15 and 20 pounds after giving up on barbequed foods (tough call). As a result, he’s dominated the line of scrimmage.

He’s not the only one on the Chiefs’ defense, though. As good as he’s been, others have also stepped up to the plate and made big tackles. The omnipresent Tamba Hali is still a strong run defender, as is fellow outside linebacker Justin Houston. In addition, inside linebackers Derrick Johnson and Akeem Jordan have been able to scrape over and clean up running lanes. Altogether, they’ve combined to create a gap-shooting, line of scrimmage establishing, stifling run defense that made life very difficult for the Cowboys in Week 2.

It’s 1st-and-10. Tony Romo is under center, and after a motion by stud tight end Jason Witten, he has a balanced trench with one tight end at each end of it. Behind him is one running back, DeMarco Murray. This is run personnel and, predictably, the ball’s set to be run by Murray on a zone stretch to his right.

Defensively, the Chiefs are in their usual 3-4 reduction defense. One four technique defensive end on what proves to be the back-side of the play, one nose tackle at the one technique also on the back-side and one three technique, Poe, is on the front-side. Four linebackers accompany the defensive line, one of which is Johnson, the inside linebacker.

At the sound of a hike, Romo takes the snap and stretches out to his right. His right arm extends as his shoulders turn to Murray, who paces himself laterally while monitoring the Chiefs’ front. He’s looking for an alley to form in the middle or potentially one on the backside. If all else fails, he has to stretch it to the right flat.

Once Murray hits the line of scrimmage, he’s met by a gap-shooting Poe. Poe wasn’t able to be handled by Mackenzy Bernadeau, a struggling right guard who has issues dealing with power. Poe has power and quickness, making him one of the league’s toughest match ups on the interior. The former quality, in particular, is a factor here because it allows Poe to stack-and-shed the blocker, and then penetrate into the backfield. If not for a last-second tumble, he may have made the tackle on Murray.

That’s O.K., though, Johnson did. While Poe punished Bernadeau, Johnson eluded right tackle Doug Free’s woeful second-level block attempt. Johnson first started flowing laterally with the design of the run, taking hard steps to his left and forcing Free to move laterally as well before climbing to the second level. Johnson is a “speed reader,” as former NFL defensive coordinator Al Groh used to say, meaning he goes through his keys quickly, and it shows here. He quickly identifies the flow of the run and then brings his shoulders together before he fires through the B gap where Poe has fallen.

His speed and tenacity through the gap, along with Houston’s knock-back of Witten on the edge, forces Murray to keep running to his right, wide of any alley and right into the waiting hands of cornerback Brandon Flowers, who’s become the force defender after shedding wide receiver Dez Bryant’s block. Murray slows down to try and protect himself against Flowers, only to be steam-rolled by Johnson for a loss of two yards.

Linebackers are sometimes analyzed like wide receivers by the outside world, meaning they’re looked at in an isolated matchup view. Can he cover this tight end? Can he shed that block? Can he make that tackle? All questions that focus on a solo effort.

It doesn’t always work that way, however. A linebacker can make a great run play without ever shedding a block or tackling the running back. Sometimes just running to a spot can make fpr a great individual effort because it frees up others to make a tackle.

The ball is now on the minus 25-yard line, and the Cowboys have 1st-and-10 to go with roughly five minutes left in the second quarter. Up to this point, they haven’t had much success running the ball. A couple of decent runs, but nothing to brag about. This is their shot to brag.

With one tight end (Witten) and one running back (Murray), the ‘Boys have presented seven gaps to the Chiefs’ seven-man box. Technically, they’re a man short with only six blockers, but theoretically, they have as good of a chance of running the ball as anyone else in the league in this situation.

Immediately before the ball snaps, left defensive end Tyson Jackson repositions himself. He slides inside, moving from the five technique (outside shoulder of tackle) to the three (inside shoulder of guard), and he’s now clogging the middle of the line of scrimmage with the rest of the linemen. That shifts Johnson outside and gives him a moving head start on the run play coming his direction.

The Cowboys pull two guards, one being Bernadeau. He’s coming across the line after Free slides over to pick up Jackson and is wrapping around Free to shoot through the C gap inside of Witten. There he’s planning to make contact with Johnson, who’s smartly expanding to the outside. Johnson is moving further and further out, to the point of being behind Houston (the outsider linebacker), who’s again doing his part by setting the edge on Witten. But why? Because not only is Johnson scraping outside to pull the plug on an outside run by Murray, but he’s also widening the near gap for teammate Akeem Jordan to shoot through for the tackle.

Jordan was to the right of Johnson the entire time, and he was initially lined up roughly a yard deeper than Johnson was. This was likely done to give Jordan more time to read the play and then come up for the tackle, which he did once he ran like a man trying to avoid gunfire, scraping over for the tackle in the C gap.

The Chiefs know what quality run defense is: shooting gaps, playing fundamentally sound, and establishing a new line of scrimmage. With aggressive linebackers, penetrating defensive linemen, and willing tacklers in the secondary, they have the chance to put a stop to the Philadelphia Eagles and Chip Kelly’s madness.