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Broncos Film Room: What is the difference between Zone and Gap scheme runs?

Will the Broncos run more power in 2021? We break down the differences between the zone and gap schemes in this offense here.

The Broncos’ run game has been a foundational part of their offensive identity since Mike Munchak was hired before the 2019 season. For years now we’ve watched Dalton Risner pull out of his left guard spot to lead the running back into the second level. Believe it or not, the Broncos had one of the more diverse running games in the league in 2020: according to Sports Info Solutions’ charting 43% of all run plays utilized gap blocking, good for 5th most in the NFL. With the addition of rookies Quinn Meinerz and Javonte Williams, there’s reason to believe Denver will only look to incorporate more gap blocking going forward.

So what is gap blocking, and how does it differ from zone blocking?

Standard gap designations and hole numbering.

Zone Scheme Runs

Alex Gibbs, Gary Kubiak, and Mike Shanahan have made these types of plays a cornerstone of Broncos’ history because of its impact on the back to back Super Bowl titles to close John Elway’s career in orange and blue. Zone blocking was a critical component to Terrell Davis’ 2000 yard season, after all.

Philosophically, zone blocking is built upon the idea that every offensive lineman is responsible for an area rather than an individual defender. If the lineman is covered, or a defender is lined up in their area, the blocker will step towards the playside and block that defender. If a lineman is not covered, or there isn’t a defender in his area of responsibility, then the blocker will step towards the play and work to create a double team on the first defender they come into contact with along the line of scrimmage. Once this defender is controlled, one of the blockers will climb to the second level.

This is a big reason why the easiest way to identify a zone run is that the offensive line will all take their initial steps in unison.

It’s important to note what zone blocking requires from a running back. There is an aiming point on zone runs that the back works towards upon receiving the handoff, but he’s also responsible for identifying overpursuit. If a defender or multiple defenders vacates an area to meet the back at the aiming point, a crease can occur. Good zone runners will take advantage of this by cutting back against the grain to find the open area. This is why zone runners are generally renowned for their vision.

It’s worth noting that every team in the NFL used zone blocking on at least 46% of their running snaps in 2020 per SIS charting. Seven teams utilized it at least 80% of the time: the Dallas Cowboys, Green Bay Packers, Los Angeles Rams, Minnesota Vikings, New York Jets, Tennessee Titans, and Chicago Bears.

One reason for this is because by definition, zone blocking accounts for the unknown by design. Coaches don’t need as much time to go over different looks and how it blocks out. It doesn’t matter whether a defender ends up where he started pre-snap because the offensive lineman is responsible for an area and whoever winds up there. This makes zone runs a “safe” response to stunts from a playcalling perspective.

One other reason I believe zone blocking is so prevalent is that it isn’t as difficult to build and maintain from a roster building perspective. Lineman aren’t asked to pull, but to simply climb. Individual blockers aren’t expected to create a ton of movement at the point of attack, but rather to wall off or impede the pursuit of the defender their responsible for.

Covered vs. uncovered is a fundamental component to zone blocking.

Inside Zone

Conceptually, Inside Zone is designed to be a no loss play due to the double teams along the line of scrimmage creating enough of vertical running lanes for a back to find a crease somewhere. It often turns into a cutback play, it’s also one of the bread and butter concepts for the Broncos’ offense and arguably Melvin Gordon’s favorite play.

Per the Broncos’ legendary offensive line coach Alex Gibbs, the back on Inside Zone is reading the block on the first down lineman outside the center. If there’s space in the B gap, that’s where the ball should go. Otherwise, this defender will impact where the back takes the ball: if his helmet goes inside the goal is to run the ball upfield just outside of him, if the helmet goes outside the ball should be cut upfield inside of him. Oftentimes, a back will cut back towards the backside A-gap.

Alex Gibbs’ OL blocking rules on Inside Zone

Like I said before, the Broncos use inside zone a ton. It’s a concept Melvin Gordon, Javonte Williams, and Mike Boone should feast on this season. Below you’ll see an example of inside zone from the Broncos’ game against the Las Vegas Raiders in 2021. Take note of how Gordon makes his cut based on the defender’s positioning.

Outside Zone

Conceptually, outside zone is designed to be a no loss play play that attacks off-tackle due to the number of double teams along the line of scrimmage creating vertical running lanes, which provides the back a chance to cram the ball into a crease. Outside zone is not designed to be a sweep play, as the backs are coached to cut upfield at the line of scrimmage.

On outside zone the back is coached to read the 2nd down lineman outside of the center, not including a shaded nose tackle. If the defenders helmet goes to the inside gap, the goal is to turn upfield just outside of him, if the helmet goes outside the back should switch his read to the next inside down lineman. If that helmet also goes outside, the back should cut the ball back across his face. If the second read goes inside, the ball should be cut between the two defenders.

Per Gibbs, outside zone is blocked the same as inside zone outside of two big differences. A covered lineman who has help from the uncovered team mate should rip through his man, which will force his help to take over the block and free him to make it to the second level. Meanwhile, the uncovered lineman will execute a wide reach block in order to “piggyback” his covered playside team mate.

On 2nd and 7 in the second quarter against the Carolina Panthers, the Broncos ran outside zone. Notice how the lineman step in unison towards the play. You’ll notice how there seems to be some hesitation on handoffs between the covered and uncovered lineman, compare this to the way the center and backside guard are so quick to handoff the nose so the covered lineman is free to climb to the second level.

You’ll also notice how the Lindsay’s eyes are on the first defensive lineman after the center: he knows there’s a free defender working off the edge and has to determine his cut off the first defender along the line of scrimmage after the nose.

Split Zone

Conceptually, split zone works to build on inside zone by adding a trap element to it. For the vast majority of the offensive line, the duties are the same, they step in the direction of the play call and work through their steps to form a double before it becomes clear who can climb to to the second level.

Where things change is how the concept deals with the backside end man on the line of scrimmage. The line (and backside tight end, if there is one) leaves him completely unblocked. To the defender this can feel a lot like zone read because he’s left free, only he’ll soon enjoy the surprise of a tight end or fullback working across the formation to mash into him. This block is a kick out and creates a potential cutback lane for the ball carrier to bounce to.

Split zone is an effective counter against teams overplaying zone runs to the play side. It’s also a great way to put a talented edge defender in conflict, as he doesn’t know if he’s being read or who is coming to block him. Defenders keying off the line or back will see inside zone, but if the kick out block is effective, a crease will open up for the back to find daylight against the grain.

Like inside zone, split zone can be effectively run from just about any formation so long as the timing from the kick out block syncs up. When the Broncos used split zone against the Buffalo Bills, they added in the threat of a sweep to the receiver to sell a fake working towards the strength of the formation.

All the flow draws the defense along with it. It’s clear where the Broncos have a numbers advantage so long as the tight end can make what is called the “bim” block on the unblocked defender.

The tight end makes a successful block and forms a wall for Phillip Lindsay to make the cutback into space. Tremaine Edmunds (49) is reading past Graham Glasgow to Lindsay.

Lindsay’s cut leads him into a footrace with Edmunds and he manages to gain four yards.

Gap Scheme Runs

A gap scheme run is built around the principle that linemen will block down to use their leverage on a defender. On the vast majority of gap concepts, there’s a pulling guard creating a numbers advantage. On these concepts, the playside offensive linemen block down the line of scrimmage, making it look as though they’re blocking away from the gap where the ball carrier is running. This will leave a defender unaccounted for who is blocked by a puller from the backside. The goal is to create a hole between the puller and down blocks.

Leaving the end man on the line of scrimmage unblocked has a ton of appeal to play callers. Edge defenders often present the biggest athletic mismatch along the line of scrimmage, and leaving them unblocked forces a conflict: the defender doesn’t know who is blocking him or if he’s being read by the quarterback. This can force hesitation from play to play.

There are two easy ways to differentiate between a gap and zone scheme run. On gap runs, you’ll notice the offensive line is blocking away from where the ball is heading. You’ll also routinely notice a blocker pulling from the backside to lead the ball carrier. This creates what is called a “down block kick out” at the point of attack.

An example of a gap blocking scheme with the backside pulling.

The ball carrier’s decision making is more straightforward on gap scheme runs. He isn’t asked to to make multiple reads to find the crease, but rather display patience to set up and maximize the blockers in front of him. Ideally the back stays close behind his puller in order to force a defender to pick a side, which the back can cut up off of.

Where zone blocking concepts were designed to avoid losses behind the line of scrimmage, gap blocking is geared around creating a numbers advantage at the point of attack. If everything goes as planned and the players execute, the offense gains a numbers advantage towards the playside and the ball carrier finds himself running free into the second or even third level.

Gap blocking is also especially useful in situations where there are extra defenders along the line of scrimmage, as this creates easy down blocks. This is why you’ll so often see it utilized around the endzone. One reason I believe gap concepts are going to be on the rise around the NFL is it’s a natural counter to the Tite front defenses are incorporating more and more to combat the spread passing games.

Power

Many coaches consider power “God’s play” for it’s simplicity, versatility, and foundational impact. On power, the frontside blockers to the center will block a gap down while the backside guard will pull and work towards the unblocked end man on the line of scrimmage. The backside tackle will hinge block in order to protect the space vacated by the pulling guard.

Power can be run from a wide variety of personnel groupings. With a fullback or H-back on the field, the backside guard will lead through the hole with the back kicking out the end man on the line of scrimmage. Worth noting that the NFL at large has mostly moved away from these heavier variations of power outside of short yardage and goal line situations.

This isn’t to say teams have stopped using power, in fact, the Broncos utilize One-back power out of the shotgun so much that it may be the defining concept of Dalton Risner’s NFL career so far.

Notice how the Miami Dolphins have all of their heavy defenders located between the tackles, which leaves them susceptible to down blocks. Also notice how Garett Bolles steps back to hinge block on the backside while Dalton Risner pulls from his guard spot to meet the unblocked Edge on the frontside.

On the following clip, Risner meets Kyle Van Noy (53) and creates the alley for Melvin Gordon to run through.

Counter OH/OF

For an offense that frequently mixes inside zone with power, it only makes too much sense to mix in counter OH/OF. It’s a way to take advantage of a overaggressive pursuit and also creates what amounts to a long trap on an edge defender, with the backside guard pulling to create a big on big block. This helps to create another thing for Edge defenders to be cognizant of at the snap.

The point of attack looks like the backside of an inside zone play with the frontside blockers stepping in unison towards down and leaving the edge unblocked, only the pulling backside guard will meet and kick him out. It also adds in a blocking back or tight end, who’s initial pathing looks identical to split zone before he leads up through the hole.

Counter OH is a fantastic changeup given the Broncos’ other bread and butter concepts.

The back’s job is to sell the initial step before accelerating to and through the point of attack. This Phillip Lindsay carry against the New England Patriots is a textbook example of what counter OH can do to freeze a second level defender until it’s too late.

At the snap Nick Vannett, Garett Bolles, and Dalton Risner step in unison to create a wall that looks like inside zone. Meanwhile Dalton Risner and Andrew Beck are on their way from the backside.

Risner kicks out the Edge while Beck leads through the gap, springing Lindsay to the open field.

Pin and Pull

A sweep run designed to attack the perimeter, the Pin and Pull or Pin-Pull takes advantage of down blocks and multiple pulling lineman to escort the ball carrier into the second level. The blocking assignments are fairly straightforward: if a playside lineman has a defender head up or shaded to his inside shoulder, he’s to pin with a down block.

If there is not a defender lined up to a lineman’s inside shoulder, he’s considered uncovered. The uncovered lineman proceed to pull and lead around the edge. The pullers will work to block any second level defenders on their way. It’s worth noting that while the example below illustrates pulls from the Broncos’ guards, any offensive lineman could turn into a puller on this play.

The backside lineman work to eliminate pursuit that could lead to a tackle for loss.

Violent poetry in motion.

What about duo?

One concept the Broncos use that can be easy to miss is duo, which utilizes gap blocking up front without a pulling blocker. It can be hard to tell duo apart from inside zone. The difference lies with the offensive line.

Unlike inside zone, the blockers don’t step in unison toward the same direction on duo. Instead, they step towards each other in an effort to create a double team on their assignment and in turn vertical displacement.

Even without a puller, duo is about creating a numbers advantage at the point of attack: it simply does so by utilizing double teams. The line will create a double along the line of scrimmage before working up to the second level, with the center blocking back towards the weakside linebacker while the frontside tandem works up towards the “Mike” linebacker.

One area where duo is quite different from the vast majority of gap blocking runs is the onus it puts on the ball carrier. His initial aiming point is the outside leg of the play side guard, but where he winds up depends upon his read of the Mike linebacker. If the Mike leverages the inside gap, the back should look to cut towards space. If the Mike leverages the outside gap, the running back should accelerate to and through his initial aiming point.

You’ll notice on the play above that the Broncos are in a very clear power situation. Plays like power or pin and pull don’t make much sense when Melvin Gordon truly can’t afford to go down in the endzone. Duo mitigates the risk by emphasizing vertical displacement above all else.

On Cushenberry’s snap he and Graham Glasgow step towards the defender between them. To their right, Calvin Anderson and Nick Vannett do the same. Notice how the left side of the offensive line is stepping away from Cushenberry.

As Gordon receives the handoff, his eyes are on the Mike linebacker.

With the Mike leveraging the B gap, Gordon cuts back towards space.

Zone blocking vs. Gap blocking

Beyond the actual coaching points for each individual concept, there’s a couple of fundamental differences between gap and zone blocking that are worth closing with.

First and foremost is how the concepts work philosophically. Zone runs work around the idea that the back will be like water, finding a hole where the defense isn’t. Gap runs have a hole in mind before the ball is snapped and depends on the offense imposing their design upon the defense.

The second difference is how each scheme creates leverage on a defender. Zone asks the blockers to step in unison and work in tandem to overtake and wall off defenders while each lineman runs along their track. Gap asks lineman to block down the line of scrimmage from their initial starting spot and away from the hole, as this creates an advantage from the jump.