The 3-4 defense’s invention is accredited to Bud Wilkinson at Oklahoma back in the 1960s, essentially as a variation on the 5-2 fronts that were most popular at the time. Indeed, the 3-4 fronts still in use today are basically 5-2 in terms of alignment, but the responsibilities of the Ends/LBs have greatly changed. Bill Arnsparger independently created a 3-4 defense in Miami under Don Shula in the late ‘60s because he had a linebacker who was better standing up than with a hand down. This is usually the way that new popular defenses are created: a coach looks at what he has, and decides to give players a duty that fits their skill set. It is rarely just a fit of genius that invents a brand new defensive scheme.

Terminology

Before we get into anything too deep, it’s best to develop some terminology. In talking about football, we commonly use the term "technique" to denote two separate things. One is the way they line up on the field, and to understand the front a defense presents it is imperative that you understand the way they line up and why.

The line numbering system is an invention of Bear Bryant, and everyone in football uses it. The position of the defensive lineman (DL) in relation to the offensive lineman (OL) is denoted by a number that starts from 0, the Center’s head. Beginning from 0, or the Nose as commonly called, the numbers go outward to each side, up to 9.

Fig. 1- Defensive line gaps and numbering system.

Linebackers (LB) follow the same numbering system, but so as to not cause confusion, their position gets the added "0" on the end, if the LB is moved off the line of scrimmage (LOS). For example, the inside LB in a 4-3 or 3-4 front may align himself behind the Nose Guard (NG) and would get a position technique of 00. If he aligns himself behind the 3 technique, his position is denoted 30, and so on. In the 3-4, the outside LBs can align on the LOS, and in that case I will not assign the extra 0. Whether they have their hand down or are standing in a 2-point stance really doesn’t matter.

The second meaning for the term "technique" is what you would think of it actually being – a way to do something. Pass rushing involves technique work, as in hand usage and placement or footwork, for example. So as to not cause confusion in the rest of this article, I’ll use the shorthand term "tech" to define position techniques. The NG is a 0-tech, the defensive end (DE) plays a 4-tech, etc.

There are differences between the DE and NG positions between the two variants of the 3-4 defense. In any of them, the NG must be the guy who is unblockable by one OL. He’s going to be the heaviest player on the defense. He has to command double-teams on almost every down. His height is not so important but his motor is very important. DE positions in the 3-man front can vary based on scheme, but these tend to be players who are either not fast enough or tall enough to play DE in a 4-man front.

Another set of terms we have to discuss is the names we use to identify the four LBs. In a 4-3 its easy: WILL, MIKE, and SAM. Rarely do you still see 4-3 teams denote them as Razor (right OLB), MIKE, and Lazor (left OLB), but it is possible in some schemes. In the 3-4, there are a few more possibilities for their names, but I’ll define them the way I learned them. The weak inside LB is MIKE, the strongside inside LB is TED, the weakside outside LB is JACK, and the strongside SAM. Older schemes use the terms RUSH and DROP to denote outside LBs, since one usually blitzes and one drops into coverage almost always. RUSH would be JACK in my terminology and the DROP LB is SAM. Another term for TED is MAC or WILL.

JACK is a hybrid player, more like a small DE who is not heavy enough to play DE in the NFL or major college ball. Usually he’ll be very quick and fleet of foot, but the lack of weight makes him a liability to a 4-3 defense against the run. To play DE every down you need weight so the Tackle isn’t pushing a feather. The SAM is the bulkier of the two outside ‘backers and needs to be more fluid and able to cover TEs yet also maintain leverage against reach blocks from Tackles and Tight Ends (TE).

Of the two inside ‘backers, MIKE is the true prototype linebacker. He has to be the stronger one and able to withstand blocks from offensive linemen most often. He needs to have strong instincts and a high football IQ. MIKE is commonly a 2-gap defender, no matter what defense you run. TED is usually going to be a little smaller and better in pass coverage, but still an excellent tackler.

Fig 2 – 3-4 Okie Front. Both Tackles and the Center are covered. The inside LBs cover the two gray shaded regions on the Guards, these are the bubbles in the Okie front.

Both inside linebackers are aligned over "bubbles" in the defensive front. A bubble is a weak spot, or uncovered gap in a defensive front. If the NG aligns in a 0-tech with the DE’s in 4-techs, the bubbles are over the two uncovered Guards. If the NG aligns in a 1-weakside tech with the DE’s in a 5-tech weak and 3-tech strong, there is a bubble between the 1 and the 3 (strong A-gap) and another between the 1 and the 5 (weakside B-gap). Where players line up tells you which gap they are assigned to defend.

A little history

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. This also makes it difficult for an OL to get an angle on a defender. Speed is not a requisite to play DL in a two-gap system, though the initial step is always a plus for DL.

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. Their primary responsibility then becomes to maintain the pocket and push their offensive opponent into the QB. If the QB steps up, he should step right into their grasp. 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.

One has to realize that against the offensive schemes of the time, which were all what we would call "pro-style" in today’s terminology, were primarily run-based offenses. Downfield passing was being developed in the NFL, which spurred the switch from the 5-2 to 3-4, but games of 30-40 pass attempts were not as commonplace (excepting a few teams or the AFL) as they are now. Player size was nowhere close to what we see now in football and finding the big planet-sized guys was a problem. Having your linemen play read techniques and keeping linebackers closer to the line of scrimmage made perfect sense.

As you are forced to drop the linebackers into coverage more and more, you are forced to pull them back from the line of scrimmage in their initial alignment. Doing so can open up holes in the running game and hurt your pass rush. This, along with the success of Jimmy Johnson’s defense in Miami and later Dallas, spurred development of the 4-3 fronts.

Fig. 3 – The Miami/Over front against a pro-I formation. The Over front presents two big bubbles covered by the OLBs, who are smaller and faster players than commonly used in the 1980s. Generally they are safeties in high school and bulked up in college to play linebacker. Recruiting high school linebackers to play DE puts more speed on the field. Auburn is predominantly an Over defense.

It was apparent that the read & reacting two-gap 3-4 had lost its edge. 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 often, 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.

So now the question becomes "Why is the 4-3 losing favor now?" and "How did the one-gap 3-4 take its place?"

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. Once you do, he’s hard to pay in the NFL with cap restrictions. You need two of them to play a 4-man front properly. It is much easier to find a guy 6’2-6’3" 245 and put him at JACK, yet blitz him enough to get adequate pass rush. Note that this does not mean a 3-4 coach would not like to have the prototypical 4-3 DE, just that he’s harder to find.

Another reason 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. With 4 men on the line at all times, and multiple WRs to cover on every play, you cannot do as much as a defensive coordinator to confuse the offense. 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. This is why some teams, namely South Carolina and TCU, base out of 4-2-5 packages. It is easier to adjust the scheme when you recruit the extra speed and numbers for an extra safety position.





Fig. 4 – Look at the problem I’ve presented this 4-3 Under defense. Who will cover the slot receiver? Either the WILL walks out to cover, or the SS must come down. If the SS comes down, they cannot play cover 2. If the WILL is no match for the H, this defense has a serious problem. What if then the offense runs the ball weakside where WILL was standing?

Additionally, the rise of the zone blitz in the 1990s under Dick LeBeau and Dom Capers in Pittsburgh aided in the complexity of the 3-4 against the passing game. With 4 possible blitzers, you could blitz a new linebacker on every play and send him through a different gap each time. That forces the offense to scheme for each of those possibilities – adding complexity to the offensive coach without creating an inordinate amount of material to teach the defenders.

This, combined with the rise of the spread, is why Nick Saban switched from the 4-3 base he used at LSU in the early 2000s to the (predominantly) 3-4 base he runs at Alabama, though his is a bit more of a hybrid than a true 3-4. He has 4 linebackers to play with on every snap. Even if he has to walk someone out, he still has 3 – enough to shift and remain sound against the run. He can play his match zone defense, which is safer against the pass, and still get sufficient pass rush and confuse the college QB thanks to the zone blitz.

In the one-gap 3-4, you have a blend of the 4-3 and the older two-gap system. As the recruiter or NFL scout, you don’t have to find the prototype DE. You can take a guy that is a ‘tweener’ and put him at DE or LB. 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. With the multiple blitzers and blitz angles on top of that, one can see that this can become a bear for offensive coaches to deal with.

I am not advocating the one-gap 3-4 defense over the 4-3, each can be used successfully and one is not "better" than the other in general. 3-4 coaches will showcase the same fronts as 4-3 coaches; it is just that they are doing it with different players who may have slightly different abilities. Often, a one-gap 3-4 team will be blitzing one outside LB on every play anyway, effectively making it a 4-3 against the pass. Fans get tied up with old stereotypes about different schemes too much. A coach can win no matter what scheme he uses, so long as he can communicate it and effectively use the talent he possesses.

Technical differences between the 2-gap and 1-gap 3-4:

The 2-gap alignment puts both Ends in 4-techniques on the offensive Tackle’s head. The NG plays a 0 tech, on the Center’s head. Both offensive guards are uncovered by linemen, creating two bubbles over both guards in the defensive alignment. Inside LBs stand over the bubble in any defensive front to keep it gap-sound. See figure 2.

The gap that the DL attack is selected based on the release of the blocker. They wait to see which way he goes, and then squeeze the gap. If the OL goes outside, you squeeze his outer half – meaning you push him into the direction that makes the hole on his outside smaller. If he goes inside, you squeeze his inner half. You are tightening up the hole the RB intends to enter and keeping that OL off the LB who is supposed to make the tackle.

When you play a 2-gap 3-4 this way, you really need mammoth defensive linemen, and in particular the NG. They all have to control that blocker and be able to tackle on either side of him, which is difficult to do. The NG in any 3-4, 1 or 2-gap, is the most important player on the defensive front. Any 3-4 team without a good NG will have a bad run defense (see Georgia Tech).

Additionally, with 2 linebackers covering two bubbles, you require big inside backers who can handle a block from a guard on every play in the event that your linemen cannot keep them free.

The type of coverage and defense they then play, in part due to the size, is usually a read-and-react style. Defenses like this drop the linebackers in zone coverage most of the time and usually only one of the outside ‘backers is a "Rush" linebacker, who attacks off the edge to generate a 4-man pass rush. The most prominent example of this style nowadays is the New England Patriots. The contrary example of a blitzing two-gap 3-4 would be the Pittsburgh Steelers.

The one-gap version is set up as a more aggressive style of defense on every snap. I believe much of it can be accredited to Bum Phillips. His son Wade runs it still today. It is very closely analogous to Under front 4-3. Most pro teams that do not use the 3-4 are playing the Under. The two defenses are very similar.

Fig. 5 – The 4-3 Under defense applied to a pro-I formation. Notice that there are two bubbles, one in the weakside A-gap and another on the strongside B-gap. However, because the 3-tech protects WILL, he does not need to be a big linebacker. He is analogous to TED in a 3-4. The 1-tech, also called Shade NG, pushes the Center weakside to make this an almost one-bubble front. SAM lines up either in a 7 or 9 technique depending on his size and skills. The weakside 5-tech is called the Bandit, and is analogous to JACK in a 3-4, though more of a dedicated pass rusher.

The one-gap 3-4 disguises the bubbles in the front better (than the 2-gap), making things more challenging for the offense to attack. Here the strong side DE slides to a 5/6-tech and the NG slants his body to the strongside A-gap. The weakside DE usually sets up in a 4i tech (a 4-tech slightly inside). The NG is still supposed to take up 2 blockers on every play, and remains the most essential player on the front. Having him line up in one of the A-gaps naturally puts him on the C-G to that side most of the time. With those DL in place, you shield your inside linebacker from direct blocks from the OL, so larger inside LBs are no longer necessary.

Fig 6 – A one-gap 3-4 front described in the text above. The strongside DE can be aligned over the TE in a 6-tech, in which case the SAM will back off the line. JACK and the 4i present a double-team problem for the left tackle above.

With the DL lined up and protecting the ILBs, versus the pass you can do more with twists and stunts between the two positions. Delayed blitzes from inside ‘backers are more common in this defense. The DE can jump outside while the OLB comes inside on a blitz, called a twist. You can do it from either side. This is one area where the 3-4 has a slight advantage over the 4-3 Under.

Fig. 8 – A double twist blitz. The JACK waits for the 4i to step out and comes across the OT’s face inside. If I feint a blitz from MIKE, the Guard could be distracted and not see JACK coming. Apply the same idea to the strong side.

Still, the job of the DL is not to absorb blockers in this version. They are tasked with penetrating their assigned gap, though the NG a bit less so than the other two. The DEs are often undersized compared with true DTs in a 4-3 front. Because of this, there is a near constant LB blitz from somewhere. The OL just doesn’t know where it is coming from.

As stated above, the DL in 2-gap play squeezes one side of the lineman he faces and keeps the blocker occupied until he can make a tackle or the LB get there. Here in 1-gap play you charge into your gap at the same time, pressing guys down the line. Now the offense has to account for the DL getting into the backfield and making plays. The extra quickness from the smaller ILBs means they can get around their blocker should he get free.

The challenge comes more for the front 7 when it comes to converting from run to pass plays. Against the pass the 1-gap End has to be a pass rusher. He needs to be quicker than a 4-3 DT, whereas against the run, the size and ability to press his blocker is more important. Guys who play DE in this defense are usually shorter and stockier than a 4-3 End, but not quite heavy enough to play DT and withstand double-teams constantly.

Coverages and blitz schemes

Like the Under defense, the one-gap 3-4 plays plenty of Cover 1 MAN coverage, with the idea being that the added QB pressure allows them to take a few risks in the pass defense. The Free Safety (FS) covers the deep middle of the field while the cornerbacks (CB) have man coverage outside and attempt to funnel their opponent towards the middle of the field where they have help.

Others continue the coverage schemes of the Pittsburgh Steelers with the zone blitz and matchup zone coverage. Todd Grantham does all of these things, as does Saban.

Matchup zone coverage is also called combination coverage. It is analogous to matchup zone in basketball: you are assigned a zone to defend, but any man who enters that zone is picked up man/man. The other type of zone is called spot-drop zone, where a defender drops to a spot on the field and remains there with his eyes on the QB so he can react to any throw.

UGA plays a mix of combination coverage and man/man coverage schemes, but is primarily a C2 zone defense with rolling C3 against spread formations in their Nickel package. Since the one-gap 3-4 is a pressuring defense like the Under 4-3, the man coverage is primarily based on man/man pressing packages using a single high safety and a "robber" underneath that is usually a linebacker. In any man/man scheme, the cover man is aligned with the correct leverage to funnel his receiver inside to the FS or to the boundary – i.e., towards the cover man’s best help. An alternative commonly used is 2 Man, with dual high safeties, that operates on the same concept.

Blitzes

Teams that use 3-4 schemes do use a few more zone blitz packages compared to Under 4-3 teams because in the case of the 3-4 you are usually blitzing and dropping linebackers, whereas in the 4-3 you’re dropping a DE. Zone blitz schemes catch the quarterback off-guard by dropping players into coverage where he assumes there will be a mismatch or uncovered zone because he reads a blitz. To be sound, and not give up big plays, they almost always have Cover 3 coverage behind them with a rotation of the coverage to one side (e.g., quarter-quarter-half instead of 1/3-1/3-1/3).

Now we want to illustrate a few blitzes from the 30-series fronts, both man/man and zone blitzes. There are obviously endless ways to blitz a QB and all have been thought of, but the choice of who to blitz and who to drop really depends on the individual talents of the player. It’s up to the coaching staff to identify those talents and utilize them the best way to win the ballgame.

The first simple blitz is a Combo blitz that alters based on the formation the offense shows. It can be a 2-gapped front or 1-gap. The secondary is in Cover 1 coverage and both OLBs blitz outside. When the offense presents a 2-back formation, the inside LBs take the first back that comes out to their side in man coverage. If one of them blocks, the free LB becomes a Robber.

SAM is aligned head-up to outside on the TE (7 or 9 technique). On the snap, he rushes outside around the TE and the strongside DE goes into the B-gap. The SS picks up the TE in man/man. The offense will rarely keep both TE and a RB in for blocking, but just in case this happens, the SS holds his position and looks for a crossing receiver or a late release.

JACK rushes outside the weakside OT, with the weak DE inside. This effectively double-teams him. The NG can pick either gap.

Quick alterations to this simple blitz are SED –where the SAM and SDE switch their gaps and the SAM twists inside to the B-gap (DE goes outside and plays a Containment role), and INDIAN – where the SAM goes towards the OTs outside hip and the SDE goes to his inside hip (a double team). Similar calls can be made for the weakside blitzers as a changeup for the offense to plan against.

The next simple blitz is called a Gut-X blitz. We keep the same coverage responsibilities except for the linebackers. Here MIKE and TED are blitzing, but crisscrossing on a pass read. TED aligns in his normal position, but goes to the weakside B-gap on the pass read. MIKE heads towards the weakside A-gap after TED crosses his face. The NG now is playing a one-gap responsibility and heads to the strongside A-gap.

The reason why we don’t want to just send the ILBs up the middle is because it doesn’t present a pickup problem for the offense. The guards will see them coming if they are uncovered. We want to double-team one of the guards so that one man will get through the line. Quite often the guard won’t know who he has to block for a split second, and both could get through.

To remain sound against the run, the SDE in this particular blitz needs to play 2-gap style, so we move him to a 4-tech at minimum. One could reduce him to a 3-tech and back the SAM off the line as well. If TED blitzes to the weakside, the strongside gaps on either side of the OT may be uncovered if we don’t.

A weakside zone blitz is another simple one to add. To make it more complicated, I’ve added a coverage rotation. When you draw up a zone blitz and plan to drop a defensive lineman, you want to give him a short zone over the middle to cover. It’ll be pretty rare to have a DL who can cover any amount of ground – otherwise he’d be a LB already. To compensate, one of the other dropping linebackers has to know that he has additional ground to cover because there is a DL beside him in zone. These plays are not designed to give any time for the QB to pass, but if the blitz is picked up, the linebackers alongside the dropping DL must be cognizant of their teammates’ abilities. In this case, my weakside rotation brings the FS down into the flat zone where he’ll be able to help the dropping DE.

There is no reason why we cannot call Cover 2 behind a zone blitz when playing a 3-man front as base, but Cover 3 is more of a "safe" call so we don’t get beaten deep.

There are almost endless possibilities for attacking an offense with a combination of zone and man blitzes, and multiple fronts that can be used to disguise what is coming. If Todd Grantham learned anything from Nick Saban though, it would be the need to stress fundamentals. If your fundamentals are sound, you’ll find that the scheme itself will not matter. A player well-instructed in his fundamentals will do well no matter where you tell him to line up on the field.