New Eagles head coach Chip Kelly has said repeatedly that he does not need a specific type of quarterback -- i.e. a dual-threat performer like Michael Vick -- to run his offense. Kelly offered a brief glimpse into why that statement is true during the Eagles' preseason opener last Friday, as he tweaked his team's attack depending on which of the five (!) quarterbacks was in the game.
We're going to put one specific formation, which Kelly used with either Nick Foles or Matt Barkley at QB, in the spotlight here. It's a one-back, pistol set, with a tight end and receiver stacked on each side of the field. That "stack" concept should become pretty obvious when you see it in the shot below, but it essentially means that the Eagles lined up a tight end at the line, with a receiver directly behind him:
This is the first time Philadelphia broke out this look. It came after Foles had replaced Vick at quarterback.
With the much more athletic Vick under center, the Eagles can utilize traditional read-option plays. In its most basic form, the read-option asks the quarterback to single out the defensive end on whichever side the running back is lined up. If the DE crashes down toward the back, the QB is supposed to pull the football and take off toward that vacated area of the defense; if the end holds his ground, the QB is supposed to complete a hand-off, the idea being that the DE's hesitation will open room up the middle.
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Philadelphia's offense out of that stack formation basically aims to do the same thing. Only, rather than having the quarterback read a defender with the option to run, Foles's choices were to give the ball to his RB or to throw a screen to one of his receivers. This is what is known as a "packaged" call. The eminently readable Chris Brown offers up some additional explanation (and video) in his breakdown of the Eagles' opening-game offense, over on Grantland.
But back to the snaps that we're focusing on, the ones in which Philadelphia ran out of its stack formation. Running back Bryce Brown was to Foles' left on this play, meaning that Foles's read is to that side of the field. Again, option No. 1 is to hand the ball to Brown; option two, unlike if Vick were running this play, is to find a receiver -- in this case Riley Cooper, who jab-stepped to the line, then fell back into position to receive a screen pass, while TE Zach Ertz blocked the cornerback in front of them.
The read here for the quarterback is as much on the extra defender out wide (a linebacker in this case, but on occasion a safety) as it is on the defensive end. When Foles opted to hand off on the play pictured above, the Patriots still had two defenders planted outside, one of which was free to take Cooper. Foles made the right call to let Brown carry the football.
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This situation presented itself again later, when the Eagles were in the red zone. In that instance, the Patriots actually lined up three defenders, in about a 10-yard window, over the stack formations on each side. That gameplan left only five defenders to take on five offensive linemen straight up the middle. Foles handed it off again, and the Patriots were totally outmatched.
Foles had an opportunity to take advantage of the pass option folded into this playcall later, only to hand it off again for a minimal gain. Perhaps the Eagles had a straight run call on here, but if the decision was left up to Foles, he made the incorrect one.
Already, pre-snap, you can see the Patriots cheated two players down off the outside as blitzers ...
The defender to Foles' right (it appears to be No. 58 Marcus Benard), where Brown was lined up on this occasion, crashes toward the hand-off. His decision to do so reverses where Philadelphia has the advantage -- instead of a numbers edge inside the hash marks, Foles had it outside with WR Ifeanyi Momah.
A split-second after Foles handed the ball off, this is how the field set up:
The Eagles had TE Brent Celek out blocking a New England cornerback at about the 35-yard-line, and Benard had read run and collapsed the edge. Had Foles pulled the ball from Brown's gut and delivered it to Momah out wide, there would have been no one between Momah and the end zone but that blocked CB and a deep safety.
(The run by Brown also could have gone for a big gain, had Philadelphia's receiver up top blocked down on the edge defender there, thus allowing Brown to turn the corner.)
Another variation on this formation came in the fourth quarter, with Matt Barkley at QB. Unlike before, when Foles had kept his eyes focused to the strongside, Barkley took the snap and immediately pivoted to his blindside for a screen to Greg Salas. This might have been a predetermined call or could have come from Barkley's read of the defense pre-snap.
It both worked and didn't. The Patriots swarmed the play, and Emil Igwenagu (No. 41) missed that all-important block on the press corner. So, WR Greg Salas was in a heap of trouble when he caught Barkley's pass.
Thanks to some shoddy tackling, Salas managed to worm his way into the end zone anyway.
This was a defensive win, right up until Salas dodged two defenders -- by shedding that Igwenagu block and getting an extra player to the ball, the Patriots had flipped the numbers advantage into their favor.
That's obviously the opposite of the goal for the Eagles here, or in any read-option attempt.
Even from these few plays, though, we get a sense for how difficult Kelly's offense can be to prep for and defend against. There are any number of slight adjustments to be made to keep the defense off-balance.
This inside run/WR screen combo does not have to be utilized exclusively from the stack formation, either. Philadelphia ran it at least once, in fact, from a traditional X-Y-Z three-receiver set. It could stay in the playbook with Vick on the field, too, though his athletic gifts make it less of a necessity.
The governing idea behind a spread offense -- hence the name -- is that by "spreading" the field sideline-to-sideline with personnel, the defense has to react in kind, thus leaving gaps and mismatches in key spots. When Vick is on the field, the Eagles can cash in on that by asking their QB to get outside; when Foles, Barkley or a less-mobile quarterback is in the game, Kelly can turn to formations like the stack and plays like this read-option with a WR screen to quickly push the ball wide.