Keying the H-back Versus Y-off or “I” Formations

One simple coverage tweak can add numbers into the box and free up your LBs versus Y-off offenses.

I learned about using a “key” read on an offset TE (H-back) in 2017 when I heard Don Brown speak at the Lone Star Clinic in College Station. In his words, he stated, that without City Check (Cover 1 with keying safeties), he didn’t know where he’d be as a coach. Those are powerful words from one of the best defensive coordinators in college football. Sometimes you need an extra fitter on the H-back, especially as more Spread teams base out of 11/20 personnel sets (Y-off), and this was exactly what I was looking for.

Don Brown’s City Check or “Key/Fox,” as Dave Aranda (LSU)/Todd Orlando (Texas) refer to it, is a Cover 1 adjustment to any two-back formation, and can also be used if the H-back turns into a traditional TE on the line of scrimmage. Both safeties are aligned 8-10 yards deep at the edge of the box and are keying the FB or offset TE depending on personnel grouping. This is a great way to give a two-high look pre-snap (Quarters), then add numbers post-snap (gapped-out single-high). Below is a diagram of Michigan running the scheme versus a 21p “I” Twin formations.

01 Key vs 21p

Both safeties are slightly tilted in and focusing their eyes on the FB. Whichever way the FB inserts or moves, the safety to that side will trigger down to “cap” the box fit. Most defensive coaches want plus numbers in the box. The term cap refers to the third man responsible in the fit. There should be an inside and outside shoulder player on the ball carrier. The “capper,” or third fitter, caps or tops the fit.

Inside the box, the LBs are focused on the RB, and if the back were to go out for a pass (more likely versus a Shotgun offense), the LB to the RB’s side would take him. The rest of the secondary is locked on their man. In terms of pass coverage, the safety away from the inserting FB will work “through the Post,” creating a Cover 1 look. Below is a clip of the play illustrated above, a simple Iso from 21 pers. I Twin.

The motion by the Badgers’ FB triggers the safety to the nub-TE’s side to start working down. Wisconsin is used to seeing City Check from Michigan and understands how to manipulate the trigger. The open “A” gap is actually away from the motion, and the FB works back to it on the snap of the ball. Inside the box, the LBs must understand the leverage of the secondary and how the FB’s movement will trigger one of them. In the clip above, the ILB hits the FB away from the dropping safety (referred to as “boxing” the block), essentially forcing the ball carrier to the safety. The overall result is a short gain.

Even with the pre-snap manipulation by the Badgers, the “City” concept was able to eliminate a big play. Iso is a great complement to Zone teams because it creates man-for-man blocking. Both LBs see an open gap and have to fill. That’s their job, except one of them needs to read out of their fit or the fit is a man short. Brown’s City Check eliminates the conflict for the ILBs. They just need to key the RB and fit their gap. If a blocker comes, box to the sinking safety. Another plus versus the run is that the safety is not considered in the fit and can be used as the plus-one, as shown above.

Versus a pass, the distribution will play out just like Cover 1. The safety to the FB’s side will take him and the LBs will divvy out the RB if he releases. The secondary is locked on a man pre-snap and the safety away from the FB’s movement will work through the middle of the formation topping the coverage. The clip below shows Wisconsin in the same formation and pre-snap movement. This time, Wisconsin opts to run a complementary play-action.

It is easy to see how keying the FB in a traditional “I” offense can be helpful to a defense. The dropping safety adds an extra player in the box that the offense can’t handle. The added player also frees up the ILBs to fit their gaps. This type of secondary rotation is great for teams that use single-gap fits too. By eliminating a read for the ILBs, a defense can free them up to be ultra-aggressive to the ball.

When playing a modern Spread offense, keying the H-back can be just as useful. The Cover 1 concept eliminates any pre-snap RPOs and forces the offense into the box where the defense is about to insert an extra man that the offensive line can’t account for. Below is a diagram of a typical Y-off Spread Iso. The Mike and Will fit their gaps and read the flow of the RB. The Mike meets the inserting H-back in the gap and “boxes” the block back to the BS and Will.

02 Key vs 20p Iso

As stated earlier, the term “box” refers to the shoulder a defender hits when attacking the block. Boxing tells the defender to hit a blocker/puller on their outside shoulder, forcing a cutback to other defenders (back inside). In the case of the diagram above, the Mike boxes the Iso block and forces the RB to run directly into the dropping safety. This is why the LBs must know the rules for the safeties when utilizing a “key” check. If the Mike were to “spill” the H-back’s block (hit the inside shoulder), the RB would work to open space and away from the dropping safety.

Outside of the physical “tackle box,” The Ni is manned up on the slot’s bubble and the FS is working “through the Post.” By keying the H-back the defense was able to get three defenders on one blocker. Even if the Will LB doesn’t rock back from his gap, the safety is there to make the tackle near the line of scrimmage (LOS).

As illustrated above, a “key” scheme doesn’t have to be limited to use against a traditional power offense. The modern two-back or Y-off Spread has become a mainstay in most modern offenses. The use of a TE that can be on or off the line of scrimmage allows the offense to be multiple in its attack. Just like against a traditional scheme, a defense can use the “key” technique to take away the ability for offenses to work the H-back either way to create an extra gap.

Plays like Iso, Split Zone, Arc or Slice Reads (“H” works across like Split Zone), Power, and Counter create multiple avenues for the H-back to insert into or outside of the box. Add quick motions (Jet, Orbit, or Push) and BAsh (back-away) concepts and there is a lot for a LB and secondary to watch. This is a reason Y-off formations have become even more prevalent.

Keying the H-back enables a defense to rotate with the H-back so the numbers are in the defense’s favor. As shown prior, the safety to the side of the blocking backs flow is the plus-one in the fit, or what I call the “capper.” The clip below illustrates the usefulness of keying the H-back. Ole Miss uses a weak stack to run Counter back to the two-WR side. The FS triggers instantly and the backside safety (BS) works to through the Post. The result is a limited gain by the Rebels.

LSU’s DC, Aranda, has used his “Key” coverage versus teams that like to move their H-back post-snap. This allows the safety to come from depth where he is not addressed in the blocking scheme. This post-snap movement also frees up the ILBs to cross-key or single-gap fit where needed. The diagram below shows the fits as seen in the above clip. Pre-snap, all RPO options are inhibited, forcing Ole Miss into the box. The Ni’s outside alignment helps him versus WR screens and the press to the boundary doesn’t open up the “Hitch” read for the QB.

04 Key vs CTR (S)

With offenses having the ability to put the TE on or off the ball, who does the secondary “key” if the TE is on the line? The answer is simple, check to your basic Cover 1 rules (or Match 3). For instance, if a Y-off team aligns the TE on the ball in a traditional Pro Twin (TE to single WR side with two WRs opposite), the safety to the TE will sink down and take him. The safety to the two WR side will then have the Post. Verus Trey, the safety to the TE will man him up, with the safety to the single-WR side working through the Post. A simple and sound adjustment (shown below).

06 11p Check (C1)


Using your safeties as a plus-one fitter versus Y-off teams can be a great answer to loading the box from a hybrid defense. This type of Cover 1 check can free up the box players to be aggressive and versus RPO offenses, the defense has everyone covered pre-snap. As the Spread evolves or devolves, depending on how you look at it, back to a power run game, defenses are going to need answers. Keying the Y-off man can be a simple and effective tool in any scheme. The scheme is easy to hide too. If utilizing a Robber/Bracket scheme to the two-WR side where the Ni is outside alignment and the safety reading mesh, it is easy to hide the “key” adjustment (this was illustrated in the LSU clip).

It is important to note, that coaches like Aranda and Brown have used this scheme less often than previous years and opt for other ways to combat Y-off formations. Brown relies heavily on his “Travel” or “Follow” concept that I’ve discussed in a previous article. Being multiple is crucial when facing a Y-off Spread offense. The ability to add numbers in different ways can keep an OC on its toes. If you don’t feel comfortable living in man, you can always play the “key” scheme as a Match 3 concept. What is undeniable about the “key” concept is that it adds numbers and plugs gaps. Everything is accounted for in the box, and that is a great place to start.

Need help with Y-off or 20 pers. offenses? MQ has you covered:


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Author: MatchQuarters


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