Back in 2012, then at the University of Oregon, new 49ers head coach Chip Kelly gave a talk to a group of coaches at the annual Nike Coach of the Year Clinic. "Every coach has to ask himself the same question: ‘What do you want to be?’" Kelly told his audience. "That is the great thing about football. You can be anything you want. You can be a spread team, I-formation team, power team, wing-T team, option team, or wishbone team. You can be anything you want, but you have to define it."
Compared to college football, we don’t get quite as wide of a spectrum in the NFL, where there’s a high level of homogeneity from team to team, but Kelly’s point remains: teams must have an identity.
Regardless of what type of offense a coach wants to run, all (successful) offenses share a structure around a set of core, base plays. These are your bread-and-butter plays that, on paper, beat the defense you’re expecting to see on game day. Kelly’s offense, as we’ve discussed over the past couple weeks, is built around the inside zone. He wants to spread defenses out, make them defend the entire field, and then run the ball down their throat.
Good defenses, however, are going to scheme to take away these base plays. They’re going to have adjustments to the defense you drew up on the whiteboard to stop what you do best — e.g., to thwart your run game, maybe the backside defensive end crashes hard down the line of scrimmage or the outside linebackers start to cheat inside or the safety drops down to load the box.
Enter constraint plays.
If your base offense works because it beats the sound defenses you drew up on the whiteboard, constraint plays work because the structure of the defense gives it up — i.e., your opponent is willingly compromising one facet of their defense to bulk up another. Constraint plays exploit these compromised areas of the defense.
It’s the draw play that works because the defensive line is flying upfield to rush the passer. It’s the bubble screen that takes advantage of an alley defender sneaking into the box to stop the run. It’s the quick slant thrown over the linebacker who’s a little too eager to shoot his gap in the run game. It’s the naked bootleg versus the defense flowing a little too aggressively to the outside zone. Constraint plays make defenders pay for getting out of position and encourage the defense to get back to the sound defenses you expected on the whiteboard, so you can get back to your bread-and-butter.
When it comes to Kelly, those who label his attack as "gimmicky" or an "east-west offense" are often mistaking the ways he constrains a defense with his base offense. Much of Kelly’s base offense attacks north-south, therefore, many of his constraint plays attack east-west. And often, these constraints are built right in to his base run concepts…
Many coaches refer to the quick passing game as an extension of their rushing attack. Kelly takes a very literal stance on that statement, frequently combining one of his base run concepts with quick passes in the same play. These "packaged plays," or run-pass options (RPOs), allow the quarterback — and really, the defense — to determine the best option after the snap based on the action of a key defender or two.
On any given play, Kelly’s quarterback might have three or four options at his disposal — handing the ball off to the running back, keeping the ball on a zone read, throwing a screen, or throwing a downfield pass. The quarterback’s job is to determine where he has a numerical advantage, read the action of the designated defender(s), and get the ball to the appropriate place. The most basic version of Kelly’s RPO package involves adding a simple bubble screen to the backside of a running play.
For most of the offense, this is no different than any standard run play. "No matter what, we’re blocking whatever zone play or man scheme, whatever the scheme is for the run blocking, that’s what we’re blocking," Eagles center Jason Kelce told PhillyMag.com of the offensive line’s responsibilities. "Most of the time, I get the running play, and I don’t really know what the quarterback’s doing.
"All the reads for the most part are designed to take advantage of what the defense is giving us, and you never really truly know until after the ball’s snapped. And then guys expose themselves on what gaps they have, what responsibilities they have, and that’s what it’s designed to take advantage of."
Outside the box is where things begin to deviate from your standard run play. By adding a bubble screen to the backside of the run, the offense has a built-in option to take advantage of the defense that overloads the box and doesn’t properly account for the receivers split wide. The quarterback will check the numbers pre-snap, looking to see if he has an advantage in the box or out wide. If everyone is accounted for outside, the quarterback will simply hand the ball off to the running back. But if the defense is a man short over the receivers, the quarterback fires a quick pass to the bubble screen.
This decision is based off the action of a key defender — usually an alley defender, such as a slot cornerback, safety, or outside linebacker, but it can change based on the specific offensive and defensive alignments on a given play. Simply, it’s about making a defender be in two places at once — Do I defend the run or the pass? — and getting the ball where he’s not.
More traditional play calling effectively comes down to guessing right. If you suspect the linebacker is creeping up too far toward the line of scrimmage to stop the run, you call the pass play hoping that he does the same thing. Packaged plays defer this decision until after the snap, when the defender has already declared his intentions, allowing the offense to determine on the fly if the run or the pass is a better option. It’s option football for quarterbacks who can’t run the option (though that’s not to say a quarterback keep option can’t be built in as well).
If we take a couple of steps back, we can see why packaged plays are a natural fit in Kelly’s offense. By spreading the field with receivers, Kelly forces defenses to remove players from the box, helping crystallize the front for the offensive line. By putting the quarterback in the shotgun and making him an extension of the blocking scheme with the zone read, Kelly is able to neutralize the defense’s inherent numerical advantage. On the whiteboard, all of this allows him to more easily do what he really wants to do: run the ball up the middle with the inside zone.
But if the defense begins to "cheat" in their alignments to better stop the run, meaning they’re no longer in those sound looks that are drawn up on the whiteboard, packaged plays give the quarterback the option to make the defense pay for getting out of position after they’ve already declared their intentions. Once the defense gets back to playing "honestly," Kelly goes back to pounding the rock up the middle.
Everything is amplified by the up-tempo no-huddle approach, which limits the defense’s ability to disguise pre-snap and increases the likelihood that someone doesn’t get aligned properly.
If there were an aspect of Kelly’s offense that was truly revolutionary, this would be it. As Chris B. Brown, writing for Grantland at the time, said, these packaged plays "are at the forefront of thinking about football." But as Brown touches on in the same article, Kelly was not the first coach at a major program to start combining run and pass concepts in the same play — that was Oklahoma State — and he’s not even the only coach running them at the NFL level. Numerous teams, including the Packers, Steelers, Seahawks, Panthers, Chiefs, Vikings, Titans, and Lions, have all effectively incorporated packaged plays into their offense. It’s a trend, along more up-tempo no-huddle, that doesn’t figure to go away any time soon.
For reference, here are several more examples of Kelly’s RPO concepts, all of which utilize similar thinking to what was described above.