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Curtis Peterson

Former Offensive Line Coach

Glenbard North High School

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Editor's Note:  Curtis Peterson recently was an offensive line coach at Glenbard North High School in Illinois. Before that, he was the runningbacks and linebackers coach at Crawfordsville High School in Indiana. He recently relocated to Indianapolis and he is the publisher of Strong Football.  You can follow on twitter by his handle, @CoachCP.

I've been a big proponent of the I formation for many years. Until recently, I was opposed to the offset I formation though, because of the tendencies it offered a defense. I can now say I am a proud convert. At Glenbard North, we utilize the offset I formation out of 20, 21, and 22 personnel. To make the I formation more effective, you need to use the fullback to your advantage. There is a big belief that, besides maybe inside zone, if you follow the fullback post- snap in the I formation, he will take you to the play. There is also a common belief that you can look where the fullback is offset pre-snap and bump to that side because the offense will likely run it that way. As an offense though, you can use that myth against defenses. This report will show some of the ways that teams I’ve been a part of have kept defenses on their toes by being creative and efficient with fullback movement, both pre and post snap.

Split Flow Plays Using a Non-Crossover Path

We have split flow plays as well that we run without a crossover path. What is a crossover path? A crossover path occurs when the fullback needs to cross the middle of the formation to get to his blocking assignment. So in these cases, a non-crossover path occurs when the fullback does not have to go across the middle of the center to execute his block. In addition, split flow means the tailback and fullback are going in opposite directions post snap. I like split flow, non-crossover plays because the fullback blocks on the backside of a play. This way, any team that keys the fullback pre-snap as an indicator of the play direction will be out position post-snap. Also, because the fullback doesn’t have to cross the formation, if the defense keys him post snap, they will be flowing the wrong way.

Inside Zone

Maybe the most common split flow play is inside zone. Inside zone rules vary from team to team. Many teams have rules based on whether or not their play side teammate is covered and uncovered, and other teams have designed "tracks" to run no matter what on inside zone. In addition, some teams use a count system. Regardless, one similarity for most teams that run Inside zone is that the fullback is responsible for a backside defender. I've run Inside zone where the fullback kick outs the backside end man on the line of scrimmage (EMOLOS), and I've run inside zone where the fullback blocks the backside inside linebacker. Both schemes work well.

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Overall, Inside zone therefore presents the I formation with a great asset, the ability to separate the flow of the tailback and the fullback. Teams that spy the fullback will be flow the wrong way with their initial steps, often making the defender quickly "over flow" to recover. This is ideal on inside zone, because when the linebackers have their momentum too far to the play side, the tailback can cut up to the weak side A/B gap (commonly known as the "back door" on inside zone) for a large gain. For this reason, inside zone is top fullback tendency breaker.


Another split flow play is Dart. Dart borrows its blocking scheme from Iso, with the only changes being the tailback's steps, and the fullback and backside tackle exchanging responsibilities.  The tailback sells weak side iso before bending back to the strong side. The pulling tackle would treat the pull in the same way the backside guard does on Power. Just like on Iso, the quarterback needs to make sure he doesn’t "push" the tailback off his path. This play is fantastic because it allows you to attack downhill quickly while giving the split flow. Also, because the initial same side flow of the backs, you will provide an "open window" that will likely get ignored by some linebackers where they would typically blow it up. It’s this open window that the tackle pulls into, typically giving him plenty of time to get to a second level defender.

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Counter GT

The final play is probably the most common play that I formation teams use to split the flow, and that is Counter GT. The GT stands for Guard and Tackle. On Counter GT, the guard and tackle both pull across the formation. Depending on if it’s run to the strong or the weak side, either the fullback alone or the fullback and tight end will have to work to cutoff backside defenders. The blocking scheme is very similar to Power on the play side, as everyone is responsible for their inside gap or a play side combination block to a backside linebacker. The guard is responsible for the kick out though, and the tackle pules for the play side linebacker. The problem with Counter GT is penetration, and that’s why it scares so many teams. With two linemen pulling slow close to the line of scrimmage, any bump that one linemen could typically recover from will likely deteriorate the path of the pulling tackle. In addition, it’s a slow play (you’re pulling two offensive linemen) and the running back needs to be patient. The slow development and penetration often times let the linebackers and secondary recover. We have evolved by using a play I will discuss later, which we call Counter or Counter Full.

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Overall, split flow, non-crossover plays are a terrific play to defeat pre-snap tendencies. As a play caller, if you find the linebackers moving over to the side of the offset back, or if you find that the coverage is rotating down to that side, you can use these plays. If you combine this with different receiver sets and overloaded gap or offensive line sets, you can cause major run fit complexity problems for the defense, with very little complexity for your offense. This can cause explosive plays in the run game.

Split Flow Plays Using a Crossover Path

We want to use split flow plays that has the fullback crossover the middle of the offense from time to time. These plays have the fullback starting off to the play side, but working to the backside. Remember, the crossover path means the fullback works to his assignment, which could be on either side of the play. By doing this, the backfield flow can slow down a defenses pursuit. This is also a way to incorporate a misdirection element that the I formation typically doesn’t get noted for. Again, we will recycle concepts from the offense and just use new backfield techniques.

Inside Zone w/FB Off-set

The first concept under this category is Inside Zone with the fullback offset to away from his assignment.. Typically seen executed from an H back position, running it from this spot allows the fullback and the quarterback to do a very quick trap flash fake. What this play enables is two things. It offers the opportunity for a backfield fake that the I formation doesn’t typically have. It also gives the Inside Zone play a better chance of hitting right up the field. The fullback crossing the midline should hold the linebackers and secondary. While some teams feel that inside zone is designed completely for the cutback, I feel that the play is designed to find the natural crease in the defense, and if we can do that without slowing down the flow of play, that only helps us. In addition, if teams do not honor the flash fake of the fullback, our opportunities for more yardage on a trap play increases. Depending on the athleticism of the backside defensive end and your fullback, you can have the fullback take a quick counter step to help sell the trap play as well. Overall, this version of Inside Zone can slow down the flow of the defense, whether it’s on this play or other plays.

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Another great way to make sure you can keep a defense off guard is once they start to slow their flow to the fullback, you can run fullback trap. Trap is a great way to work against the grain and up the field on the defense. Unlike many coaches, I feel like Trap can work well against a 3 and a 5 technique. At a previous coaching stop, we found out that our average yard per carry on trap to a 5 technique was nearly 3 yards greater. Every down defender outside of the defensive linemen that we are trapping is left alone since we should end up inside of this player. This offers great angles for the offensive line as well. In addition, you can sell any number of plays in the opposite direction. I prefer to sell inside zone as mentioned earlier or toss sweep, depending on what our best plays are that year.

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Having the fullback work from the play side to the backside is a terrific tendency breaker for I formation teams. It forces a defense to take the focus off the flow of the fullback.

Same Flow Plays Using a Crossover Path

While these types of plays are typically considered slow developers, same flow crossover path plays can indeed hit quick. Again, a coach should make sure he focuses on recycling the concept over and over again for his offensive line to ensure that the amount of teaching is minimal for a backfield.

Iso Swipe

A quick hitting play that fits this category is the Iso Swipe variation. I will call it Iso Swipe here to differentiate it to for this posts purpose, but in our offense we simply call it Iso and the back knows when he is offset opposite that he needs to use the crossover path to get to his assignment. Just like Iso, everything is blocked exactly the same. The fullback offsets over the guard to the backside of the play and comes underneath the quarterback. The tailback runs the play on a downhill path just like normal Iso. What this concept does is it provides the "open window" look to the middle linebacker. Seeing no fullback or pulling linemen, he typically fast flows into the gap only to be caught off guard by our fullback. Essentially this is a trap block for the fullback, except I’ve yet to meet a Mike linebacker who is taught to wrong-arm it. Even if he did, he would likely open up a gashing hole in the defense that our tailback would likely bend his path into for a big play. Again, nothing changes for us, but it presents a different tendency and look for the defense. You can expect a big collision in the gap, so we need movement in by our interior linemen in these areas, which is also the case with Iso. Perhaps the best advantage is how quickly this play hits. Because tailback is running his Iso path, the defense doesn’t have much time to react to the play. Again, while this may not seem like a big difference, a defense taking one or two wrong steps gets us anywhere from 1-3 more yards on a downhill play like Iso.

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Counter Full or H

The last play is the Counter Full or H. This play is similar to Counter GT mentioned earlier. However, perhaps the best way to teach it to your blockers is that it is the same thing as Power except the fullback and guard switch responsibilities. The guard is kicking out the end, and the fullback is wrapping for the play side linebacker. Teams teach the tailback to do the counter fake in many ways. I prefer the heel tap. The tailback steps backside with his backside foot. The play side foot taps the backside foot. The backside foot pushes off on a path to the C gap. Really, the play side foot never touches the ground on the first step. The tailback shifts his weight and after the tap pushes off with his backside foot. This creates ideal timing on the play for us for most backs, and allows us to get on a good path. This play is a slower developer, but penetration doesn’t seem to hurt it as bad as the Counter GT. This is just my experience with it, and I believe it’s because the fullback has a better path than a pulling tackle and you don’t have to worry about making sure the backside is sealed off.

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Game Film

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Concluding Remarks

Having run all these concepts before I can say they have really enabled us to be more successful in the I formation. Sometimes you want to break tendencies. Sometimes all you need to build successful drives is to have the defense to flow the wrong way initially on a couple plays so you can get a yard or two more. For information, I have began to detail these concepts and the individual player techniques in more detail on my site, Strong Football, so check it out for more information.



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