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On the 3-4 Switch and Multiple Fronts

Lots has been speculated for some time now based on our failure to bring in the top flight DE and the sheer numbers of DTs and tweener DE/DTs that we've stocked up on, as well as the superior talent at LB, about switching to a 3-4 front. Even more numerous are the comments about odd fronts and how its such a radical difference from what we've been doing. Frankly, most people talking about a 3-4 defense really don't have a clue on what Clemson really runs now, or what the addition of a few more 3-4 fronts to our scheme really means. Truth is, its just a new set of looks to give the offense, not a radical shift. If you have good players in the front 7, the numbers split dictates what you can show most often, but a scheme doesn't radically change based on those numbers splits. No coach in his right mind would completely scrap a system that worked just because he got a few good LBs or DEs, they'd just tweak the scheme to suit the talents of the players, and thats how defenses evolve anyway. 

So we thought it would be a good idea to show you the 4-3 Under again, and compare it to the 3-4 sets you'll see a little more of this year. We wrote part of this article for the UGA Maple Street Press Annual, but the one-gap 3-4 they (and Alabama) play is almost assuredly the style Clemson will show. Going to a 2-gap system would be a more radical departure in terms of scheme and teaching. The staff just won't have time to teach that style well and drill it along with the normal 1-gap 4-3 fronts. Most of what people think about when discussing the 3-4 is the 2-gap style, but the one-gap is something you'll see is almost identical to what we do in the Under front.

Lots of people say stupid things when you bring up the 3-4:

OMG how will we stop the run!?

I dont like the 3-4, how will we get adequate pressure on the QB?

GT plays the 3-4, look how well that did last year!

Virginia played the 3-4 and they couldnt win anything under Groh!!

Our linemen aren't heavy enough to play 3-4!!

These types of things are nonsense spouted by people who don't know shit about football.  If the 3-4 wasn't a sound defense to run, it would not be used by almost half of the NFL. You still have 7 men in the front and they're in the box just as much as a 4-3 defense is, so being sound against the inside run has been solved... its just a matter of whether or not you have the right players in the middle and good coaches to teach them. Sometimes its not easy to find those players, or you play in a league/conference where the minor differences do show an advantage one way or the other.

The original Okie 3-4, being derived from the 5-2, is what we call a "two-gap" system. The two-gap gained in popularity until the late 1980s, when the 4-3 Over defense stole the thunder away from it (thanks to the Miami Hurricanes and the Dallas Cowboys).  It is a system where the defensive linemen, and usually at least two of the linebackers, have the responsibility to control two gaps on the line of scrimmage. The DL play what is called "read technique" and line up directly across from an offensive lineman, not slanted to one side as they are in other fronts like the 4-3.  Linemen who play read techniques wait to read the block of the offensive lineman across from them to better determine the playcall from the offense and the direction the ball is going to go. They tend to be bulkier and heavier players, because they are taking on their offensive counterpart head-on during every play. They want to keep those linemen tied up on the line of scrimmage and allow the linebackers to make the plays. Read techniques are not hard to teach per se, so much as they are hard to rep. Its like zone blocking, in principle its easy, but to execute it well takes a lot of reps. 

Two-gap linemen, because of their added size and lack of speed, are rather poor pass rushers in general. They rarely get the same level of technique work in pass rushing, and tend to be bull rushers on pass plays. Two-gap teams also blitzed a bit less, and were more of a "read & react" style of defense until the ‘90s. This design makes it easier to drop eight men into coverage and prevent big plays as well.

It was apparent that the read & reacting two-gap 3-4 had lost its edge by the 90s because of the lack of quality Nose Guards and interior LBs. Dropping 8 into coverage didn't leave many to get sacks either. Speed rules football, and you want that speed doing something destructive to the offense. The single-gap 4-3 took the crown in football because it allowed you to teach defensive linemen less and put their speed to good use. Because they have only one gap to control, they could rush the passers, who were now beginning to throw more like Sid Gillman, without regard for keeping the OL tied up and the LBs free. 4-3 linemen all are tasked with getting the QB sacked, 3-4 linemen of the time were not.

4-man fronts require two interior linemen with the same skill set as 3-4 linemen. That is not the issue. The big problem is finding the prototypical 4-3 defensive end. He needs to be tall, big enough to take on an offensive tackle, and fast enough to get off the edge quicker than his opponent. The NFL prototype would be 6’5" and 280lbs, while being able to run a 4.7 40. That’s hard to find, plus you need two of them. Its much easier to put a guy 6'3 260 at OLB and blitz him every down.

Another big reason for the prevalence of the 3-4 again is the success of the spread offense in college football and the flexibility the 3-4 allows in attacking it. With more and more teams in college incorporating spread formations and concepts, 4-3 teams find themselves with a big problem: what do you do against 4/5 WR sets? If you play 4-3, you either walk a linebacker out on slot receivers, bring the safeties down and play true man/man, or you have to go to a Nickel or Dime defense. Once you’ve walked out the linebackers, who helps on run support? If your DL doesn’t get the RB or someone misses their gap, there is no safety net of linebackers there to help. 

In the one-gap 3-4, you have a blend of the 4-3 and the older two-gap system. You can take a guy that is a ‘tweener’ and put him at DE or OLB. You can take heavy interior linemen that are skilled at pass rushing, and put them at DE positions even if they don’t run 4.6-4.7 in the 40. The fact that it is a one-gap system and easier to teach means they can rush the passer without regard for the linebackers and put what talent they do have to good use.

I do not advocate the one-gap 3-4 over the 4-3, each has its uses. I do prefer the one-gap over the 2-gap version because it disguises the bubbles in the front better, and is simpler to teach. I'm all for adding fronts that simply teach guys new places to stand without actually changing everything they're doing. In most cases, the fronts are exactly the same, but with different personnel.

The one-gap 3-4 used by Wade Phillips and the pseudo-1-gap Saban at Alabama (his is a hybrid) is analogous to the Under 4-3 we normally run against pro-set personnel (2 back, 1TE or vice versa). Those 3-4 fronts reduce down the Jack LB so that he's doing the same thing that the Bandit DE is doing. A Jack with his hand down rushing is no different from the Bandit. People don't realize that the Bandit is called something besides just the 'weakside DE' because he does have pass coverage responsibilities in some cases. The strongside DE doesn't really do those things, and in pro sets he could face double teams from the OT/TE, so he needs to be heavier.

Now to show some differences and similarities in fronts. Remember the whole point is to control every gap in the front, and there are only so many ways to line up 7 guys. There are two broad groups of fronts, EVEN and ODD.

  • Even = Center is not covered by any DLineman. Usually this means that both the Guards are covered.
  • Odd = Center has someone over his head-to-shoulder. A shaded NG qualifies.

Thats it. When coaches talk about odd fronts, thats what they mean. They are not talking about odd being 3 or 5 men on the LOS. Even does not mean a 4 or 6 man line either.

Within those groupings, you can put every other front in defensive football. Every defensive coach will rename his to whatever he likes it to be. Miami called their Over front "Canes", for example. This is the basic set:

  • Undershift - 1-tech strongside, 3 tech weakside. In the Under defense, the Sam LB plays on the LOS.
  • Overshift - 1 tech weakside, 3 tech strongside. In the Over defense, the SDE adjusts to the TE.
  • Bear - An odd front that covers all 3 interior OL. It is usually two 3-techs and a NG playing 0.
  • Okie - Center covered, both Guards uncovered.

You should see that the term "Okie" still applies to some one-gap 3-4 fronts, because otherwise you'd have to line everybody up the same way everytime. There is a subgrouping of names for various alignments, and coaches use whatever name they feel like.


A representative Okie front. There are two bubbles, or weak spots, in the front. "Ted" is another term for the strong ILB in a 3-4.

In the Under, the defining characteristic is the placement of the 1 and the 3, and then the Sam LB. The Over is the opposite shift. Technically the Under doesn't even have to mean a 4-3 defense, it just means that the NG is shaded strongside, and the 3-tech DT is weakside, thats it. Both fronts are ODD fronts; we use a shaded NG. A 4-2-5 scheme will show you the same fronts, as SC and TCU often do.

Even fronts go by a few names, most with the collective term "G" applied in some way or another. Virginia Tech runs G-fronts (a 2i and a 3 technique usually) quite often. We'll have a post on their defense later this fall. Clemson also runs G-fronts. One is called "40" or "40 Point" or "40 2 Slide". They usually have pretty dull numerical names.

Between Bear, Under, Over, and G, you have all the ways that a team that bases out of a 4-man front can line up. Some are even and some are odd. In every defensive scheme, you want a mix of both for variety.



Clemson for the most part runs out of the Under, because the teams we play are more pro-style systems and the Under front is the best way to defend them. Spread formations and personnel groups give it a few problems as I aluded to above. You don't have to play Under with 4-3 personnel however. Saban calls his Base Under O.


Alabama's 3-4 Base Under, a 1-gapped front.

Compare it to the 4-3 version:


The weakside 5 is the Bandit, and he actually does have pass responsibilities on the backs in general. Notice the WILL is protected by the 3-tech from a direct block. SAM is playing a 9 outside the TE.

Usually when I draw the fronts, I dont use small adjustments that are commonly made. The Bandit does not always play a 5-tech, and most of the time here he doesn't. He plays a Crash 6, which is a little wider off the OT. You can see Jack does the same things in the same CR-6 technique. I would say the essence of the position difference is that Jack is more likely to peel off in pass coverage than the Bandit. As such, he'll be a few pounds lighter because he won't have to deal with an OT every play anymore. Sometimes the Jack will rush without his hand being down, whereas the Bandit nearly always has a hand down. Its easier to see when you watch how the 3-4 adjusts to spread sets.

Saban's system is interesting because though his base is a 30 front, he is using both 1-gap and 2-gap principles. Most of his fronts are 1-gapped, and particularly when they adjust to spread sets. Only a few of their 3-4 fronts are actually 2-gapped, so he doesn't have to spend tremendous time repping read techniques. To play these fronts you require better WLB play because now he's doing many of the same things that MIKE is doing in the 4-3.  He's not protected as often by the 3-technique from blockers.

Here are a few of the fronts we'll be using:


This is the Alabama base 3-4 front with alignments in parentheses, which is the same base front used in the NFL by the Cowboys, Dolphins, Patriots, etc. A Heavy-5 technique is the actual term for what the SDE is doing in the 4-3, and it just means his job is to squeeze any veering OT. Technically this front is 2-gapped and the DEs can go either way, B or C, but often the WDE goes inside with Jack outside in the C-gap.


This is a split (even) front, and it falls into the "G" front family. Compare it to the Under front.


This shade front is termed so because the NG is shaded and the End on the weakside, who is normally playing a 3-tech in the 4-3, is moved a half step inside to cover the OG directly. He is the one on the front who plays a 2-gap job, but everyone else is 1-gapping.

Now to show how the 3-4 would adjust to a spread set as opposed to a 4-3.

Notice how Jack is aligned in a Ghost, up and outside as if the TE was there. He's better equipped to pick up the Tailback in pass coverage here, or take the flat zone weakside. In the 4-man set, the Bandit would be doing the same thing, but starting from his hand being down. He'd have a tougher time getting over to the flat zone however.

Notice how the Jack is now walking out, before, in the 4-3 base, you would either sub SAM out for Nickel, and/or walk out the WILL on the slot (H) man to the weakside.

But the true advantage to the 3-4 vs the 4-3 is in blitz angles, which is the subject of another post entirely.