Defending the I Formation Post Snap Cover 3 Rotation

Defending the I Formation with Post Snap Cover 3 Safety Rotation


Defending the I formation, especially a well coached team, can be a daunting task. If the quarterback can throw play action, and the offensive line is physical, while also pounding you with their best athlete at tailback, a defense could be in for a long day. Add a little bit of the option or quick passing game, and this formation quickly turns into a very versatile and lethal complete offense.

One way LSU used to defend the 21 personnel, 2×1 pro I formation was with post snap safety rotation. Brophy’s LSU video by Pete Jenkins under Saban inspired this post, because at one of my first coaching stops we executed a similar tactic. I feel like it’s become lost in the shuffle with today’s spread offenses, but it’s an easy to utilize defense that inserts an extra, often unblocked defender at the point of attack while also defending the middle of the field and deep passing game fairly well.

Defending the I Formation Post Snap Cover 3 Rotation

Fullback goes left, Free Safety Comes Down, Other Safety to Deep Middle Third

Let me start with this statement, this adjustment isn’t designed to be adaptable to the Spread, as Coach Jenkins advocates. It’s designed to stop what the I formation does best. This is a lesson every defensive coach needs to learn. Running “catch all” plays that work against all formations will lead to disaster. Have plays or at least checks based off of a teams formation tendencies. For instance, if you call cover 3 and the team is in 21 personnel 2×1 pro, use post snap safety rotation. If they come out in 2×2, maybe stay in 3 if you like that, or check to something else like Quarters. Take away what the offense presents to you. This coverage specifically is used for defending the I formation.

Defending the I Formation: Identify the Backfield Key

Most I formation teams have some sort of backfield key. Most likely its the fullback. Maybe its the tailback. This is determined on a week to week basis. This backfield key will determine safety rotation. Fullback is the obvious one for I formation teams since they tend to rely on them heavily.

Also, the Linebackers need to be able to understand the key so they know which way to spill a lead block from a fullback. That’s why fullback is also easier, because Linebackers and secondary run fits often depend completely on the backfield flow.

So make sure your backfield key is a back that is easy to identify for both linebackers and the two safeties. If I had to pick, when defending the I formation, I would select the fullback. If it was a split back team, I would venture to say you could probably drop the safety to the initial dive back, though that may give you problems if both backs come up in pass protection. Another option for those teams is obviously to defend one back, perhaps their biggest playmaker, and use him as the key.

Defending the I Formation: Cover 3 Responsibilities

It’s important to simplify the coverage responsibilities across the board so your athletes continue to play fast. For instance, in the diagram below, the Sam and the Will both have the flats. The Mike has the hook to curl area opposite the key backs direction. Both corners have their respective deep third.

The only difficult one here is the backside hook to curl defender’s responsibility, so the Mike in the diagram. However, this person, in my opinion, is a run player anyways so if they utilize play action, we’re not surprised if he is slightly out of position.

I won’t go into exact details on how to play Cover 3, there are numerous articles and books that cover that topic. The biggest thing though is the safety rotation. Prior to the snap, the defense is in a 2 high, middle of the field open (MOFO) look. After the snap, the fullback can work in 3 directions. He either goes right, left, or right up the middle. If he goes up the middle, we automatically assume he is going to the tight end side. When it doubt, the fullback is to the tight end. It’s important the safeties call the side as they rotate for pass coverage and run support reasons. Run support reasons are described in the next section. The backside safety should shuffle and sprint to the deep third, eyeing any immediate #2 vertical threat as he does. Again, for pass coverage details, check out any resource on Cover 3 hook to curl responsibilities.

Defending the I Formation: Run Support Concerns

I like a Strong or Weak call for safeties as they rotate into the box post snap, for run support and pass drop reasons. If it’s to the strong side, the Mike knows he’s spilling the ball to the safety and lead block. If it’s a Weak call, the Mike knows he is forcing any blocks so the ball carrier goes to the Will linebacker and Safety to that side. The Will has similar rules to his side. This changes up the way you take on blocks when defending the I formation’s best plays as well.

Defending the I Formation Iso Play Post Snap Rotation

Defending the I Formation Iso and Dart Plays with Post Snap Rotation. Notice the different reactions of the Mike based off of the call he gets from the safety.

See the diagram above on how I formation Iso play and Tackle Wrap/Dart play would be defended with the safety rotating weak. Tackle Wrap is the same thing as Iso as a blocking concept, except the fullback and tailback go different directions. Notice how this changes the angle the Mike linebacker takes on the block. Versus Iso, he has a safety supporting him, so he spills to him. Versus Tackle Wrap/Dart, he doesn’t have a “strong” call, so he squeezes the ball carrier to the backside support.

If a blocker leads up on the down safety for some reason, the safety should funnel the back to his help on his inside.

Against the option, it really depends on how you setup your front seven as well, as well as the type of option you are facing. There are a multitude of concerns here. I believe this is honestly more of a game plan basis. Who is the offense trying to get the ball to on the option, and how can you take that away best? That may mean you don’t run the Cover 3 post snap rotation if it leaves you in a bad place. Again, this is your call as a defense.

Defending the I formation with Post Snap Safety Rotation: Is it for you?

I’m an advocate of simple defense. I’ve made that clear on here. I also am a quarters guy too. I think this would be simple if you already run cover 3 a lot. But I how well it would translate for a team that operates in mainly Quarters variations.

I wanted to show something on Strong Football that I thought was interesting and has been effective over time. If you run cover 3, this may be a nice little addition versus your 21 personnel, 2×1 pro style opponents.  It is simply a great way for coaches to adjust who have trouble defending the I formation from Cover 3. It should be relatively simple, and easy to check out of if they motion to a slot look (just rotate to the twins side). It can give you a nice advantage versus the standard I looks, especially if the team has a heavy backfield tendency.

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One thought on “Defending the I Formation with Post Snap Cover 3 Safety Rotation

  1. Kevin Tallman

    Coach, great and insightful articles that you have been posting. I would love to see some of your thoughts and concepts on how you might defend the Wing T offense. Some schools are abandoning the spread because of personnel issues and going back to more of a power game.

    Coach Tallman – Cosmos Football

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