Max Gap vs. Back Gap Fits in 3-High Spacing

Feb 14, 2022 | Three High Coverage Structures, Front, Defense, Coverage, Odd Front Structures

By Mike Kuchar with Joel Taylor
Defensive Coordinator/Linebackers
Mercer University (GA)
Twitter: @KoachTaylor



Coach Taylor’s initial motivation came from the success he was having using Drop 8 coverage in the pass game. He transitioned from three-down into four-down specifically to defend Samford University, a SoCon opponent that can sling the ball up and down the field. The Bears surrendered more than 400 yards through the air against Sanford back in 2020, so something needed to be done. So, he backed up a pair of eyes- by putting his boundary End at the second level- and put more vision on the quarterback in zone coverage. He played two versions of Drop 8, from both a halves and a thirds structure. We profiled both of these coverages concepts already in a prior report.

But while Coach Taylor was enamored with how the coverage eliminated windows in the pass game, it was how he was defending the run that consumed him. "The coverage doesn’t matter until you stop the run," he recounted. "When we were playing teams like Sanford that was playing with tempo we continually wondered how we're going to stop the run? That's when I came out of the Rabbit hole and came up with what I came up with.”

What he came up with was an adaptation of his two-high quarters run fits and complemented from three-high alignments. He took his back gap principles made it fit from 3-high structures. And he was able to do this by teaching a “loaded box” vs. a “bump box” run fit based on the formation structure. “It was simple teaching,” he told me. “I studied it and made simple rules that fit our defense.”


Mercer Personnel:

The Bears utilize a three-high safety defense on more than 20% of snaps this season. They essentially play with the following personnel:

  • Nose
  • Two Defensive Tackles
  • Boundary Defensive End (Kat)
  • Mike LB
  • Sam LB
  • Will LB
  • Free Safety- Middle Safety
  • Nickel Safety- Field Safety
  • Boundary Safety
  • Two Corners


Like most Odd front outfits, the Kat outside linebacker can play both on the line of scrimmage and off the line of scrimmage. While he needs to be cross-trained to play coverage, according to Coach Taylor it's inexpensive and advantageous to do so. This way the Bears don’t need to change personnel to keep this structure intact.


Front Structure and First Level Fits: “Rely on the Knockback”

While Mercer played most of the 2021 season in a Mint (4-0-4) front structure, Coach Taylor has made a conscious choice now to move to reduction fronts. He’s going to do so by setting the reduction to the side of the back. The image below is a base alignment vs. 2x2 open sets, which will be explained later in the report.


He'll play with a Zero nose that will only be responsible for one gap by lagging into the backside A gap. The defensive end away from the side of the back will play a "knockback" technique by owning both the C and B gap based on the block of the Tackle. If the Tackle works to reach him, he'll fit the B gap and push the ball to the Sam or Will. If he gets any down block, he'll close the hip and expect to spill any blockers coming to him. “We just tell them to let that offensive tackle reach you and get that ball pushed to the overhang,” said Coach Taylor. “When teams stretch game us, we have them fall inside instead of playing outside so that the backer can fit off of it.”


“Back Gap” vs. “Max Gap” Run Fit Methodology:

In Mercer University's defensive system, the entire run fit is based on a simple premise: if you are inside the box, you spill. If you are outside the box, you box (contain). The idea is contrary to typical one-high, 8-man fit defenses because Coach Taylor wants the ball pushed to overhangs as much as possible.

It’s important to note that in the Bears defensive system, there are two forms of Drop 8 coverage. Both come from 3-Deep, 5-Under spacing. One of which is a cover three variant, where the field and boundary safeties are inserted into underneath coverage to play hook curl, the Sam and Will play the flat and the Mike has the high hole.


The other variant is a cover two variant, where the field and boundary safeties are pure halves defenders. He calls it "Frog" because the Middle Safety acts as a "Tadpole" playing the middle of the field from the top down.


Coach Taylor will teach two separate run fit scenarios based on those two structures: Back gap vs. Max gap:

“Max Gap”- Cover 3 run fit. This means defenders own the gap to their side. This is very similar to an Odd Stack run fit.

“Back Gap”- Cover 2 run fit. Defenders can back gap the run game based on the mesh of the quarterback. This fits with the "hold and fold" technique (referenced below) that Coach Taylor used in quarters coverage.


Since the majority of Mercer's Drop 8 coverage falls into that cover two variant, most of Coach Taylor's run fit patterns fall into back-gapping principles. But these principles are separated into load box vs. bump box scenarios which are classified by the formation and are detailed in this report.