Last week, the Philadelphia Eagles beat the Los Angeles Rams.

Believable? Sure. Especially if I told you that would happen in the beginning of the season; or before Carson Wentz returned from his ACL tear; or before Philly’s secondary was ravaged by injury.

But I’m telling you that this week — a week in which the Eagles are 7-7, holding on to wild card hopes by a thread, wondering what could have been in the games they all but gave away: Tennessee, Carolina, Dallas (twice). Nick Foles was the starting quarterback; second-year backup Rasul Douglas and 5’9 rookie Avonte Maddox were the outside corners; Timmy Jernigan, Derek Barnett, and Jordan Hicks were all missing from the starting lineup.

The narrative will follow Foles: a champion, returned to his throne, piling yet another improbable win on a heap of cringeworthy evidence for #QBWinz truthers. But underneath the Season of Saint Nick, the real agent of Philadelphia’s improved offense labors, unannounced and unassuming.

For the first time all season, Philadelphia played consecutive games in which 12 personnel out-snapped 11 personnel; and it’s their highest-scoring two-game streak to date. As a matter of fact, Week 15 was the greatest difference between 12 and 11 personnel snaps in a game Philadelphia played this season; and it was their second-highest scoring effort of the season.

(Remember, 12 personnel is a 1 RB, 2 TE, 2 WR grouping of players. 11 personnel is 1 RB, 1 TE, and 3 WRs.)

The journey toward 12 personnel usage has been a bouncy one. In the beginning of the season, with Alshon Jeffery out of the lineup with injury and Jordan Matthews/Golden Tate yet to be acquired, the Eagles quickly moved toward 12 and 13 personnel. Once he returned, the tables flipped to 11 personnel (3 WR sets), and Philadelphia lost 3 of their next 4 games (Weeks 4-7) and 5 of their next 7 (Weeks 4-11).

Things bottomed out in Weeks 10 and 11, as Golden Tate was integrated into the offense following the trade deadline: Philadelphia combined for thirteen total snaps in 12 personnel across those two games, despite enjoying a 52% success rate in 12 personnel to that point in the season (46% in 11 personnel).

But in the weeks since, Philadelphia has been incorporating more 12 personnel and the formations that accompany it — even in Week 13, which saw a huge boost in 11 personnel, the Eagles were incorporating the formations and concepts that power their 12 personnel engine. The continued emergence and improvement of rookie TE Dallas Goedert, in gritty, blue-collar tandem with the ever-reliable and record-setting Zach Ertz, has built in Philadelphia an offense for which opposing teams don’t have an answer.

No better has that been illustrated than in the past two weeks, including a devastating overtime loss to the Dallas Cowboys and that season-saving victory over the NFC-leading Los Angeles Rams. In those two contests, Philadelphia scored 6 offensive touchdowns, each coming from 12 personnel. In Week 14, the Cowboys tried to answer Philadelphia’s 2-TE sets with base personnel (3 linebackers) and surrendered a 60% success rate through the air, including 3 passing touchdowns. In Week 15, the Rams went the other direction, with nickel and dime sets — Philadelphia instead ran for their 3 touchdowns, as well as a 41% success rate on the ground.

With an elite receiving weapon and passable run blocker in Zach Ertz, and a great run blocker and solid receiving weapon in Dallas Goedert, defenses are officially damned if they do and damned if they don’t. Philadelphia’s 12 personnel sets either force the nickel corner into physical run defense or the strong side linebacker into downfield pass coverage — and that’s a win almost every time.

Let’s look at what that means on the field. We’ll start with the 3 rushing touchdowns against the Los Angeles Rams — they should look pretty similar, and painfully easy to execute:

The Ace Wing (R/L) formation is a key staple of Philadelphia’s 12 personnel. It has those two tight ends tight to the line of scrimmage on one side of the formation, and two receivers flexed out from the formation on the other.

When lined up in this formation from anywhere on the field, the Eagles immediately force you to make a choice: if you play man coverage, you’re exposing your strong safety and linebacker in coverage against Ertz and Goedert. So most teams play zone, and almost exclusively Cover 3/Cover 1 (Middle Of the Field Closed) zones, because they need to get that extra safety in the box in run support.

Of course, any time you can force a defense into a predictable coverage shell, that’s a win for the offense (here, MOFC zone). But this zone coverage also forces the corner to the TE side to be a primary run defense player at the end of the line of scrimmage, which proves a huge liability: corners aren’t built to handle run support against TEs, for goodness’ sake! Most struggle enough against WR blocks.

That’s what you saw for Los Angeles. The Rams have played very little base defense (3 linebackers) all season, preferring to be beaten by the less effective and explosive 2018 run game as compared to the 2018 passing attack. And that’s exactly what the Eagles did — but instead of running out of 11 personnel, as is the prevailing mindset of successful running teams in this day and age, Philadelphia used their 2 TEs to dominate the Rams’ smaller safeties and corners.

That’s what you see on the three same-side zone runs above. The running strength of this formation is clearly set to the two-tight end side — but the line and TEs initially take zone steps toward the weak side, which force the linebackers to flow downhill and fill the A-gaps. However, this is a C-gap run, as the entire offensive line washes the defenders into the weak side, and the back plants and bangs the run upfield off the offensive tackle’s butt. The TEs are responsible for sealing off the EDGE and run support safety, which forces the cornerback to make a close-quarters tackle — and corners, generally speaking, suck at that.

And the final note: on all three of these runs, Philadelphia lines up with the strength of their formation (3 potential receivers; running strength with 2 TEs) into the boundary, or the short side of the field.

By placing the strength of the formation into the boundary (FIB), Philadelphia forces the defense to remain cognizant of the threat of speed options to the field (the wider side), in which there is 1) more space and 2) fewer defenders, which also means more space.

That threat allows them to pair their strong rushing attack out of 12 personnel with constraint and packaged plays: simple, easily executed ideas that almost act like “alerts.” When Philadelphia has a favorable match-up, in terms of numbers or personnel, with their wide receivers in the field, they can run an RPO-like play to take the free yardage.

For example, the touchdown that opened the dam of scoring against the Cowboys defense:

This is a shield screen play, which has become all the rage in goal line situations. The quick motion behind the slot receiver gives the outside receiver plenty of room to catch the immediate screen pass; and even though Dallas had a safety shaded over into that area to help their man-coverage corners, the space is too great for the safety to cover before Alshon Jeffery can get into the end zone.

Once Philadelphia sees that safety shaded over the two WR set to the field, they know the middle of the end zone will be open if they want it — so on their next red zone trip, they come right back to that Ace Wing formation into the boundary. This time, they motion out of it, to further stretch the Dallas coverage and force them to communicate and adjust — ideally, I’m sure they’d like to get out of the MOFO (Middle Of the Field Open) coverage they get stuck in, but they don’t have enough time/preparedness for that. So with two deep safeties they stay.

Sick play design here: Philadelphia fakes the stick concept with Dallas Goedert as the option route — he either settles in that zone or breaks outside. He gives a look like he’s settling in space before whipping back inside to the vacant area in the middle of the field. Easy six.

We’ve looked exclusively at red zone ideas thus far, which makes sense: again, the Eagles have scored all 6 of their touchdowns over the last two weeks out of 12 personnel. But as Dallas Goedert becomes a more active and trusted receiver for the coaching staff, 12 personnel’s mismatch problems expand to all depths of the field.

Again, it’s all about dictating coverages: as we said at the top, Dallas looked to respond to 12 personnel with their base defensive personnel (3 linebackers) to protect against the running threat, and Philadelphia exposed their linebackers in coverage.

This is a traditional 3 x 1 formation — I’d call it Trey Left — and most teams would run it out of 11 or even 10 personnel (no tight ends!)

Not Philly: their 12 personnel forces Dallas to keep three linebackers on the field, which leaves Leighton Vander Esch matched up with Goedert at the top of the screen. Carson Wentz sees a match-up he likes here — it’s clearly man coverage, and with one deep safety, Vander Esch will have minimal help to the deep outside. He checks the call into a shot play for Goedert, who beats Vander Esch off the line of scrimmage and has a step — Carson simply misses the throw.

Same situation, this time in just plain old Ace (no Wing!) — a formation ran almost always out of 11 personnel. The Cowboys have three linebackers on the field, and with the formation set into the boundary, the MIKE linebacker (Jaylon Smith) is forced to come from a poor initial leverage to cover Goedert’s out-breaking route. That’s free money right there — very few linebackers will be able to get connected to Goedert on this route, and then challenge his catch radius and physicality.

These were just the man-beaters: Philadelphia can nickel-and-dime the everliving daylights out of a defense that elects to go zone against their 2 TE sets: Zach Ertz is the best zone-beating tight end in the league, given his understanding of coverages, quick breaks, and physicality when playing with leverage.

Defenses were once built to handle the run from 12 and 21 personnel — slowly, they’ve adapted to defend the pass out of 11 personnel. Doug Pederson, Mike Groh, and Dallas Goedert now have them stuck somewhere in the muddled middle: where the threat of the run is strong and imposing, but the potential for deep passes keeps your secondary on its heels.

If Philadelphia wants to complete this late playoff push, they’ll need to continue sticking opposing defenses snugly between that rock and hard place; they’re one of the few teams — if not the only team — who can. As offenses’ receivers get smaller and faster, the Birds will tote out their supersized wideouts; as teams spread to lighten the box, Philadelphia will load it up with corners without a snowball’s chance against their hellbent rushing attack. They’ll stay ahead of the sticks by running the rock; the passing attack will explode through their mismatch TEs; and the Super Bowl Champions will look to threaten once more.