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Bob Diaco's 3-4 "No Crease" Defense

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Before discussing specific defensive players I think it is important to first discuss Bob Diaco's 3-4 "no-crease" defense a little bit. We have discussed several things related to front seven play over the years at One Foot Down. Some of those discussions were specific to the 3-4 and some of them were not. Regardless I felt like the basics of the 3-4 and some of the things that Coach Diaco does with it would be worth a review prior to talking about Notre Dame's individual defensive players. This is by no means meant to be all encompassing. The intent here is to simply take a look at the wavetops of the 3-4 defense and some of the things that Coach Diaco does with it.

Diaco's base defense is a 3-4 front with a Nose Guard, two Defensive Ends two Outside Linebackers and two Inside Linebackers. The term "no-crease" is in reference to the fact that all of those front 7 players are close to the line of scrimmage and aligned in a manner that eliminates vertical and horizontal creases between the individual players.

Diaco picked up much of his defensive philosophy when he spent three seasons (2006-2008) as the Linebackers Coach under Al Groh at the University of Virginia. Groh is part of the Bill Parcells to Bill Bilichick coaching tree that has produced several top flight coaches such as Nick Saban. As a relatively young coordinator there isn't much written on Coach Diaco's defense specifically but by studying the defenses of Bilichick, Groh and even Saban we can garner some insight into some of the things that Coach Diaco is doing with his defense we watch the Fighting Irish.


In the 3-4 front there are four linebackers lined up behind three down linemen The outside linebackers are hybrid players that are sometimes referred to as "tweeners" due to their ability to fill multiple roles on the edge of a defense. They often fill what most think of as a traditional outside linebacker role but they also need to be able to fill the roles of a defensive end with a hand on the ground, or a defensive back in pass coverage. Both outside linebackers need to be proficient in all three of those things.

The flexibility provided by those two outside linebackers is the biggest benefit of a 3-4 front. That ability to move them around to fill multiple roles allows the defense to easily maneuver in and out of 3, 4 or even 5 man fronts with relative ease. All it takes is either outside linebacker walking up and lining up as a down lineman prior to the snap. This versatility can create an additional layer of confusion for opposing offensive linemen and quarterbacks that are trying to make pre-snap reads to determine things like blocking assignments and where the pressure might be coming from.

The hybrid role of those outside linebackers is obvious but the three down linemen in the 3-4 front also need to possess some rather unique characteristics. The three down linemen also fill multiple roles and those roles might also change somewhat from week to week and often times even snap to snap. First and foremost they all need to be two gap players that possess the ability to control blockers and occupy two gaps on the line of scrimmage. Their ability to do this keeps offensive linemen from getting in the way of the four linebackers behind them as they flow to the play.

Nose Guard

The 3-4 defense all starts and ends with the nose guard. As Chris Brown has noted the nose guard must be a two gap "war daddy" that can occupy multiple gaps and blockers in the middle of the defensive front. When Notre Dame lines up in their base 3 man front the nose guard is playing a zero technique lined head up on the center. He is responsible for clogging both A gaps and taking on a double team from either offensive guard. The nose guard must be large, and physically imposing. It is also imperative that he is smart and extremely quick. As a two gap player the nose guard must not only immediately defeat the center, he also needs to control those A gaps and often has to also take on one of the offensive guards lined up next to him to do it.

In doing so he not only clogs up the middle but he creates a numbers advantage for the defense that allows the inside linebackers to flow to their gaps freely to make plays. When Notre Dame lines up in their base defense with 3 down linemen they typically leave both offensive guards uncovered. Technically those offensive guards, and B gap, are the responsibility of the inside linebackers. So when the Nose Guard is able to occupy a guard as well as the center it makes that job significantly easier for those inside linebackers.

When Diaco brings an outside linebacker up with a hand on the ground to create a 4 man front the nose guard must also be able to slide left or right and line up in a 1, 2 or 3 technique like a more traditional defensive tackle would in a 4-3. In that role he will still most likely be playing a 2 gap technique occupying both A and B gap on his respective side. Regardless of where he lines up his primary role is to occupy gaps by controlling the offensive linemen that are manning them. He should only penetrate up the field in the event that he reads pass or when a running play starts to flow to the outside. He always pursues from the inside out. "War Daddy" is a very appropriate way to describe these two gap nose guards that serve as the anchor of the defense.


Defensive Ends

In the 3-4 the Defensive Ends also fill a hybrid role. In the base 3-4 front they will line up in a 4 technique head up on the offensive tackle. They will then take responsibility for both B and C gap playing "two gap" in the same fashion that the nose guard does. But Notre Dame appears to commonly line them up in a 5 technique on the outside eye of the offensive tackle where they are responsible for C gap. This is more common on the strong side of the line where the tight end is lined up. Whether lined up in a 4 or 5 technique the defensive ends must control C gap first and foremost, and if the tight end is on his side he may also have to take on a double team to do so. He will get help from the inside linebackers on B gap. He will only shoot his gap to pursue up the field if called upon to stunt or once he reads pass. As a result these guys won't put up big numbers like 4-3 defensive ends can but that isn't their job. Much like the nose guard these guys primarily occupy blockers and control gaps while the linebackers clean things up and rack up individual statistics.

In addition the defensive ends must also be able to slide further inside and line up in a 1, 2 or 3 technique like a more traditional defensive tackle would in a 4-3. This obviously happens when one of the outside linebackers puts a hand on the ground to create a 4 man front. When this happens the defensive end could either be playing a 1 gap technique or 2 gap technique like the nose guard.

In order to be able to perform these multiple roles effectively these 3-4 defensive ends need to have a unique blend of size, smarts and athleticism. The profile is in the neighborhood of 6 ½ feet tall and 300lbs. It takes that type of physical specimen to play a two gap technique effectively in the trenches.

Outside Linebackers

In the 3-4 front the outside linebackers fill that hybrid role that I discussed in the intro. When lined up in a 3 man front the outside linebackers roam the edge of the line of scrimmage pre-snap in what I think of as a more traditional outside linebacker role. They are responsible for run fits in D gap and also have responsibilities in pass coverage. In addition they also have to be able to get on the line of scrimmage and put a hand on the ground and fill the role of a more traditional defensive end in a 4-3 front.

In Coach Diaco's sytem the two outside linebackers actually play two slightly different roles. They both require the same skillsets but use them with different frequencies. He calls the two outside linebackers the "Cat" and the "Dog." The Cat linebacker plays on the boundary side of the field and typically becomes the 4th defensive lineman when the Irish go to a 4-3 front. He absolutely has to be able to put a hand on the ground and play "defensive end." The Cat also needs to be an excellent pass rusher and more often than not he is one of the primary pass rushers in passing situations whether he has a hand on the ground or not. The Cat doesn't spend a lot of time in pass coverage but he still needs to be able to help in coverage when needed.

The Dog or "drop" linebacker is probably the toughest position in Diaco's defense. He plays the field side and primarily maintains responsibility for covering the slot receivers and tight ends in space. But he also needs to be able to cover D gap and rush the quarterback when called upon to do so. You won't see the Dog with a hand on the ground as often as the Cat. The Dog has to be able to fill the roles of defensive end, linebacker and a defensive back. This is a tall order for any player. When Diaco wants a 5th defensive back on the field that "Nickel" package typically replaces the Dog with an actual defensive back.

Both the Cat and the Dog linebackers require very similar skillsets. They just use those skillsets with different frequency. Both players are outside linebackers first and foremost. The secondary responsibility of the Cat is most likely to fill that defensive end role, followed by dropping into pass coverage. For the Dog those 2nd and 3rd roles are just flipped. The Dog is also an outside linebacker above all else but is more likely to drop back into pass coverage than the Cat is. Despite this he must also maintain the tertiary responsibility of being able to play like a traditional defensive end.

Inside Linebackers

The inside linebackers have a lot of responsibility in the 3-4 defense. Initially they have to quickly read those uncovered offensive guards to determine where they need to flow. The inside linebackers are responsible for B gap on inside runs and when they read inside run they need to fill that gap quickly and violently. If the nose guard can successfully occupy both the center and a guard they allow the play side inside linebacker to hit B gap fast as his route is unimpeded. If the offensive guard is able to release clean then the inside linebackers have to take on those offensive guards and quickly execute some block destruction as they arrive on the scene to make the stop.

If that offensive guard fires out towards the inside linebacker's outside shoulder the inside linebacker is now reading an off tackle run and must quickly move laterally to ensure that the guard does not cut him off. Pursuit is inside out with the play side inside linebacker taking an angle to make the stop. The other inside linebacker can also pursue but retains responsibility for the cutback. He cannot over pursue or a gaping cutback lane might open up and allow the running back to make a big play.

If the offensive guards show pass block at the snap then the inside linebackers have to assume their respective coverage responsibilities based on the coverage call in the secondary. Prior to dropping into coverage they have to first sniff out screens and draws. Once they have determined that isn't the case they have to quickly drop into coverage. Their area of responsibility is typically going to be what is most often referred to as the "underneath zone" though they also often pick up tight ends that are running seam routes. This is an area that Notre Dame's inside linebackers have had some issues with in the last couple of years.

Coach Diaco calls his two inside linebacker positions Mike and Will. The Mike linebacker will typically line up on the strong side of the formation and the Will lines up on the weak side. Traditionally the Mike is also the "quarterback of the defense" and is responsible for ensuring that the entire defense lines up correctly. Manti Te'o really is running the show when he is out on the field at Mike Linebacker.

The Secondary

Secondary play doesn't really change behind a 3-4 front but it does have some added flexibility. The Irish seem to spend most of their time in Cover 2 and Cover 3 and take advantage of the flexibility associated with the 3-4 front to rush 5 and still play zone coverage behind it without making any substitutions. Any time this happens it is typically referred to as a zone blitz since the secondary is still playing a zone defense behind it.

One wrinkle in Diaco's defense is that he plays a field corner and a boundary corner. The field corner plays to the wide side of the field and is typically the stronger of the two in coverage. The boundary corner still obviously maintains coverage responsibilities but tends to be a little more physical.

Due to the fact that the field corner is playing on the wide side of the field the safety tends to cheat a little in his direction prior to the snap. This often translates into the field corner getting more help than his counterpart on the boundary and getting it quickly. This can sometimes make it seem that the boundary corner is "on an island" as they sometimes get picked on specifically in the short and intermediate passing game.

Both corners have a role to play in run support. The primary difference is that the field corner has more real estate to cover and must take on blockers to prevent runs from going outside of him. His role there is to force the runner back inside where the inside out pursuit of the defensive line and linebackers will arrive on the scene to make the play.

One disadvantage of using a boundary and a field corner is that the offense can then dictate the matchups with their receivers. In turn that offensive advantage is negated somewhat by predominately playing zone coverage in the secondary.

Overall I have become a big fan of the flexibility associated with the 3-4 and I am happy to see the Notre Dame defense starting to look like a Notre Dame defense again. There are many advantages to the 3-4 defense that I think lend themselves to success at Notre Dame. The flexibility on the field is obvious but I also think that the 3-4 plays to Notre Dame's advantage in recruiting. Elite defensive linemen, specifically defensive tackles, are few and far between. The best ones typically get offered by 20-30 programs and Notre Dame has historically struggled to get enough of them on the roster. The 3-4 defense requires a few less of those guys and a few more big and athletic outside linebackers that tend to be available in greater numbers.

The 3-4 is also very technique dependent and requires players that are smart and disciplined. This requires great coaching and players that have the capacity to learn. I think that Coach Kelly has the right assistant coaches in place and they are working with a very intelligent group of players. It is a good fit for Notre Dame.

Philosophically what Coach Diaco is doing is very similar to what base 3-4 coaches like Bill Bilichick and Nick Saban have been perfecting for years. Those two obviously figured out a way to make it work pretty well for them. As we enter year 3 of the Brian Kelly era I expect to see the Notre Dame defense continue to improve. The front 7 specifically should be playing on a very high level this fall. If the secondary can get up to speed quickly the 2012 Notre Dame defense has the potential to be very good.