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Old 01-12-2009, 01:00 AM   #12
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A good but very long breakdown...

The 3-4 Defense: A Primer

I am writing this piece in response to some of the announcers and writers out there that obviously wouldn't know the difference between a 3-4 defense and a punt formation. And there might be some fans out there that do not know when they are seeing a 3-4 or a 4-3 or what the differences are. To some it might seem redundant and to others informative.
As always, I write with out the benefit of a proofer, so please ignore typos, etc.

Unfortunately, I cannot (or don't know how to) include diagrams. If some of it might seem confusing in reading I suggest the following: diagram out a typical offensive formation or offensive line. Mark the gaps as A, B, C, D with the center-guard gap being the "A", the guard-tackle the "B", the tackle-tight end being the "C", outside of the tight end is the "D". To designate the "techniques" (where the players align in opposition to the offensive line), start with the center as "0", his outside shoulder is "1", the gap between center-guard is "2", the inside shoulder of the guard is "3", and so on. Adding a "0" to any of these numbers would indicate a LB lining up off the line of scrimmage. I hope that this helps. In addition, and excellent resource (with diagrams) can be found at


The 3-4 might seem like a recent innovation. In fact, it has been around for a relatively long time. The system had been in use on the collegiate level since the 40's (Oklahoma is credited with its first use), but the defense looked vastly different as it was played very close to the line and every player was a brute. In 1970, in Superbowl IV, Hank Stramm wanted to utilize the strength of Curly Culp, a defensive lineman that was very strong and couldn't be blocked one-on-one. Stramm wanted Culp to tie up the Vikings All-Pro center Mick Tinglehoff and tie up additional guard support. He wanted to prevent the Vikings outstanding line from being able to pull and lead the great Vikings outside rushing attack. This worked out pretty well for the Chiefs as they dominated the heavily favored Vikings by holding them to just 67-yards rushing, 3 picks, and recovering 2 fumbles.

Early innovators of the defense on the professional level were Coaches Bum Phillips, Chuck Fairbanks and Hank Bullough. Today, the most familiar 3-4 with 2-gap line technique (we will get to that later) is referred to as the Fairbanks-Bullough.

In the 80's, the success of the 49ers and Cowboys with the 4-3 alignment saw most of the other teams adopt it as their base defense. However, the recent success of the New England Patriots, utilizing the 3-4, has given new life to the 3-4 in the professional football level. "It's not so much that teams are changing," said coach Bill Parcells, who won his first Super Bowl title in 1991 using the 3-4. "It's the people that have become decision makers have backgrounds in that defense and that is what they are implementing." Patriots coach Bill Belichick first learned the 3-4 while working under Parcells. Browns coach Romeo Crennel, New England's former defensive coordinator, was an assistant on the same Giants staff. Nick Saban also worked with Belichick ... and on down the coaching tree.

So why the switch to the 3-4?

Proponents suggest it's most effective in combating today's sophisticated passing attacks, with their multiple formations and intricate routes, because a fourth linebacker allows a defense the luxury of disguising its blitzes and coverages better.

If the offensive guards are responsible for blocking the inside linebackers, the center has the nose tackle and the offensive tackles are designated to block the defensive ends, who's got the two outside linebackers? And where are they?

The 3-4 also can morph into a 4-3 in the blink of an eye. The 3-4's outside linebacker can quickly come up to the line of scrimmage, drop his hand down, and voila, 4-3. Or he can stay on the edge as a decoy, pick up a running back in the flat or cover the tight end.

"I'm not saying it's better," Parcells said. "Here's what I think some of the advantages are: At any time you can drop eight people into coverage, and that complicates things for the quarterback. Not many four-man line teams have the ability to do that.

"The second thing is it's more 1-on-1 football. It forces the offense to block more straight and use less angles than a gap defense does. Sometimes that's more difficult for the offense to do."

In the 4-3 defense, you need two very large and athletic defensive tackles and two somewhat large and very athletic defensive ends. These guys are very hard to find. If you can't find a couple of good defensive ends, you're in for a long season of living and dying by the blitz.

In the 3-4 defense, you need one really large nose tackle. This NT has to be a real monster of a guy, 350 pounds or so, because his job is to take on the center and one of the guards simultaneously on every single play. Then you get two more defensive tackles at around 300 pounds each, and play them up against the offensive tackles. All three of the defensive tackles have what is called a gap responsibility. They are expected to hit the offensive linemen head on, and watch the play to make sure the running back doesn't come through on either side of them. Also, they're expected to hold their block so that the offensive linemen can't get out and block a linebacker.

In the 3-4 system, the linebackers are expected to make most of the plays. In the 3-4 system, the DTs play a more physical game as they are taking on one or two offensive linemen directly, play after play. Unlike the DTs in the 4-3, the DTs in the 3-4 are responsible for every single gap in the offensive line. Although the DTs get relatively few chances to make tackles or sack the quarterback, anything bad that happens is still ultimately their fault.

In the 3-4, you have four linebackers. Two of these guys are inside linebackers, and are expected to weigh roughly 240 pounds and be quite athletic. You also have two outside linebackers. These guys are sometimes called "tweeners," as they are in between the normal size of defensive ends and linebackers. These guys should weigh perhaps 255-265 pounds and also be quite athletic. Because these are linebackers, they tend to be faster than the heavier defensive ends. Their presence makes it much more difficult for the quarterback to roll out, as he will be rolling out directly into the path of one of these linebackers.


The 3-4 is composed of 3 down lineman, 4 linebackers and 4 defensive backs.

The defensive line positions are 2 defensive tackles and 1 noseguard. Typically, the noseguard (NG) plays head-up on the center (OC). This known as the "0" technique. The defensive tackles (DT) line up just off the outside shoulder of the offensive tackle (OT) in what is known as the the "3" technique. The primary function of the DL is to protect the LBs and play the run. Each defensive lineman is responsible for 1 or 2 gaps, depending on the scheme being used.

NG is the toughest position to fill. The NG is head-up on the OC and is responsible for defending both "A" gaps ("A" gap is the gap between the OC and OG's. "B" gap is between OG and OT. "C" gap is between OT and TE.) in the running game. He faces constant double-teams and takes a pounding. He must have size, mental and physical toughness, stamina, durability, lateral quickness, and good technique in terms of playing with leverage. If the NT cannot hold his ground, the defense is very vulnerable to runs between the tackles.

DTs tend to weigh around 290-310, and many are former 4-3 DT/DE "tweeners". They must be able to play the run well. The 3-4 DT is responsible for the "B" and "C" gaps in the running game and lines up in either the "3" or "5" technique (head-up on the OT) position. It's tough for a 3-4 DE to pick up as many sacks as a 4-3 DE, because a 3-4 DE doesn't have the freedom to go willy nilly upfield. He has to protect the LBs in order for the 3-4 to work.

The inside linebackers must be stout in run support. Because there are only 3 DL to match up against 5 OL, they must be able to stack and shed an unblocked offensive lineman in the running game. The left inside linebacker is called the “MIKE" linebacker (keep in mind that different teams might use different nomenclature for the different positions). He closely resembles his counterpart in the 4-3 except that he aligns himself in a “2" technique over the guard to the tight end side. The right inside linebacker, referred to as the “MAC" Linebacker also aligns himself in a “2" technique except he is on the “weak side” away from the tight end. In the 3-4’s most basic form both the “MIKE” and “MAC” linebackers have “A" and "B" gap responsibility, so like the middle linebacker of the 4-3 they must play the run from the inside out. However, in many of the 3-4 scheme’s seen today you see the “MAC" backer playing more of a weak side linebackers role and the “MIKE” can likewise find himself in the strong side role. The strong-side "MIKE", must have an attacking style of play to come up and meet a ball carrier at the line of scrimmage and be fast enough to string him out to the sideline. Though his first priority would be to stand the blocking back up in the hole yet plugging another running lane.The weak-side "MAC", is responsible for backside pursuit and must be disciplined enough not to overrun a play which could result in a big gain. Both players also must be able to blitz the QB and be able to drop into short zone depending on the defense called. Personnel wise the inside linebackers in the 3-4 are usually the prototypical linebacker that runs a 4.5 to 4.7 in the forty and stands 6’ to 6’4”tall at 240-255lbs. Most linebackers that play inside in a 3-4 scheme can usually translate well to the middle and weak side linebacking positions in a 4-3.

The two outside linebackers of the 3-4 defense have very similar jobs, especially in the very basic concept of the defense. An OLB in this defense is simply stated, the pass rusher. Both the “SAM” (strong-side) and “WILL” (weak-side) of the 3-4 will usually have “D gap” responsibility and will line up outside of the DE as a 5/7 technique (outside shoulder of either OT or TE). He is the guy who chases down the QB. His ideal frame is tall in the 6'4" range and normally anwhere from 240-260 lbs. Long arms are needed to disengage from NFL offensive tackles in the run game and also used in pass rush. They must be very fast as to be able to beat a Tackle to the corner in pass rush but also strong and athletic enough to utilize bull rush moves when needed. This player is also responsible for outside contain in the run game.

When Coach Hank Stram first introduced the 3-4 to the NFL it was four legitimate linebackers playing zone defense behind three down linemen. Later on teams started replacing one of those outside linebackers with a pure pass rusher and now the most prevalent version has both outside linebackers rushing the passer from a defense that more closely resembles a 5-2. On almost every play, 1 of the OLBs will rush the QB. The OLBs can play from a 2 or 3-point stance.

A cornerback (CB) in this defense has many different responsibilities from a traditional zone coverage CB. This player needs to be very fast with good ball skills as he plays alot of man coverage due to the schemes employed, dependant on what the front 7 does. Certain packages will also ask this player to play a variety of zones. The CB also be must tough enough to help support the outside run game. Normally, due to defensive formations, these players will line up on the WR with a 5 to 7 yard cushion as to not get **** the line scrimmage and surrender a deep pass play due to the extra safety playing in the box on run support, better known as cover 3. The roles of a CB vary greatly depending the defensive playcall and responsibility of the safety.

Like a Safety (S) in any defense, they must be able to play centerfield to be successful. Due to the versatility of the defense, its common to only have one deep safety in the pass game, which is why referring back the CB's will line up with a cushion b/c there isnt alot of help there. These players make all the secondary calls and must be strong in second level run support. The free safety (FS) is responsible for reading the offensive plays and covering deep passes. Depending on the defensive call, he may also provide run support. He is positioned 10 to 15 yards behind the line of scrimmage, toward the center of the field. He provides the last line of defense against running backs and receivers who get past the linebackers and cornerbacks. He must be a quick and smart player, capable of making tackles efficiently as well as reading the play and alerting his team of game situations.

The strong safety (SS) is usually larger than the free safety and is positioned relatively close to the line of scrimmage. He is often an integral part of the run defense, but is also responsible for defending against a pass; especially against passes to the tight-ends.


Without a doubt the 3-4 defense is the poster boy for flexibility. The strength of this defense rests in the number of quick footed athletes you can place on the field at the same time. It is so versatile of a defense that you could be in what appears to be a 5-2 defense on one play and then drop back in to a 4-2-5 zone on the next. Zone blitzing is especially effective from the 3-4 because you have so many players who can do similar things. You almost have endless combinations of the zone blitzes you can call. This is what has made Bill Belichick and Romeo Crennel so successful over the past; they were completely unpredictable and nobody had any idea what they are going to do next. They did so many different things every week that at times it seemed like they were drawing defensive calls out of a hat.

On the defensive line, the two most commonly used schemes are the "2" and "1" gap. In the "2" gap, the defensive lineman are responsible for the gap to either side of their technique. For instance, the NG, in a "0" technique (head up on the center) would have the job of covering either gap between the OC and the OG's. He accomplishes this by driving into the OC and then shedding him once he reads which gap the play will come to. At the very least, he hopes to tie up the OC and at least one of the OG's and keep them off the inside linebackers. Same applies for the DT's. This is why in a typical 3-4 defense, the ILB's will have the majority of the tackles. The "2" gap is usually know as the Fairbanks-Bullough, named after Chuck Fairbanks and Hank Bullough, two early innovators of the 3-4 as mentioned previously.

In the "1" gap, the defensive lineman will have a single gap responsibility. This system is not what people think of when they think of the 3-4, because the original 3-4 was/is strictly a 2-gap system. The Phillips is named after "Bum Phillips". Bum learned under Paul "Bear" Bryant at A&M and had coached high school football well enough to break into the college ranks (not a common route). He was a defensive coordinator in SD, then in HOU (that's the Oilers for you young folks). He later was a head coach in HOU and later for NO.

Phillips was an innovator who turned the 3-4 upside down. His system is one-gap. The DL penetrates, and is charged with constant harrasment of the QB. The LBs are typically fast, and at least one of them will blitz on any given play.

The reason for the near constant 1-LB blitz is to account for the fact that the outnumbered DL is also relatively undersized and only one-gapping. However, the adjustments work out well. The OL never knows who the blitzer will be, or where he will come from. The Phillips is more aggressive that the Bullough. The school of thought for the Phillips 3-4 is the need to pressure against the QB to stop the pass threat, and this is done by varying who the "fourth rusher" (who is really a blitzer) is. Add another blitzer in here and there, and the speedy/aggressive Phillips system is a threat to QBs, and attempts to get turnovers by slashing the time that a QB has to make decisions.

Another system is the Lebeau Zone Blitz and the theme for the Lebeau system is attack, attack, attack. The Zone Blitz is very nasty thing to deal with. In terms of player types, one can vary the NT type and even the DEs, but 1 gap speed DEs are much more common.

The zone blitz play (also know as a zone fire play) has been around for ages. Dick Lebeau took the play and turned it into a full system for Pittsburgh in the early 90's. He tried his hand at head coaching and being a coordinator elsewhere, but with little success. He doesn't seem to be a good manager, and isn't great at adopting to the existing systems of other teams. What Lebeau is know for it two things. His players love him (they play hard for him), and he is an excellent theoretician who develops elaborate plays with many twists.

The idea is that the different DLs will often drop back into coverage, while several linebackers (and even defensive backs) will blitz. The OL can't brace themselves, because if they do they will likely brace for the wrong assault. This is the one defense that prides itsself on turning the tables - the defensive line and the LBs hit the OL hard and often and try to wear down the other side.

CBs most often jam or jack the WRs , then either drop into zone or blitz. SAFs either zone or blitz (a safety blitz is called a "monster"), the LBs blitz most often, and sometimes zone, the DL either rushes or ends up in zone. It's a very fun defense to watch.

This defense tries to stop the run by penetrating the OL and disrupting the offense's backfield. They stop the pass by targetting the QB with heavy blitz packages. The zone blitz is very effective against screen passes, wreaks havoc against check offs by QBs (because the zones can't be anticipated, nor can the rush), and is the only major defensive scheme that is predicated on wearing down the OL instead of the OL wearing down the DL. For these reasons, the timing system used by many spread offenses can face more troubles here than in many other systems.

There is one glaring weakness. You drop a DL into a zone and the blitz doesn't hurry the QB and the QB has a quick-realease for an arm... well your defensive lineman isn't probably going to match a WR or TE going for a reception, is he?

Another scheme that makes the 3-4 so flexible is the Over/Under. In this alignment, the linebackers rotate can "rotate" or "slide" to the "Over" (towards the strong side) or the "Under" (towards the weak side). The rotating OLB moves up to the line of scrimmage and plays the "50" or "60" technique (adding the "0" means he is lined up off the line of scrimmage on the OT or TE outside shoulder). He can be in either a three-point or two-point stance. The two ILB's rotate to a "40" and "10" technique and the backside OLB now plays the "40" technique. While this alignment can easily be confused with a 4-3, it is definitely different. Either OLB can be in blitz, stunt or coverage. By moving the OLB to a "60" technique (slightly outside of the TE) it puts him in great position to either jam the TE, a speed rush, or coverage in the shallow flats. Also, the backside OLB can loop around the tackle for an outside rush or overload the weak side protection by blitzing the "A", "B", or "C" gap. The Over/Under also yields itself well to the zone blitz and makes it very easy to disguise coverages.

Finished at the link below:
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