Part 2: The 3-4 vs. the 4-3 Defense

When Chiefs fans heard the news that Gunther Cunningham may use a 3-4 defense on certain passing downs it raised more than a few eyebrows. For many, just a whisper of the 3-4 conjured up memories of the 1997 Falcon defense and the glory days of dominant Chiefs defenders. In Part two of our report we go more in depth with the differences between the 3-4 and 4-3 defense.

Differences in Personnel - The Linebackers
Now that we are done discussing the defensive line we can move on to my favorite position, the linebackers. I could easily write an entire book about the art of playing linebacker but for the sake of time I will keep this short.

Out of all the linebackers deployed in every defense there none is more important than the middle linebacker to the 4-3. Also referred to as the "MIKE backer", he needs to be the best tackler on the team as well as its most physical player. This is because the 4-3 defense is designed to turn everything back inside towards him. Since those running plays are supposed to be funneled his direction the fullbacks, guards, centers, and tight ends frequently have a bull's-eye on his chest. If the offense can defeat the middle linebacker they can also force the defense to bring the strong safety closer to the line of scrimmage and play "8 men in the box". A defense never wants to do this because when the safety comes up and plays like a linebacker it opens up the passing game since the cornerbacks now have less help over the top.

In a base 4-3 defense the "MIKE backer" is lined up in a "zero technique" with "A or B gap" responsibility to the strong side. He keys off of the guards and the fullback and uses that read to determine what the offense is trying got do. When defending runs to the outside he will often "scrape" towards the ball but wont commit to full pursuit until he is sure there is no cutback to the inside (This is especially important against teams like the Denver Broncos that employ the bootleg and cutback runs).

Technique wise, like all linebackers, the middle linebacker must keep his knees bent and maintain a low center of gravity while moving through traffic. This not only helps him maintain his balance and explosion but it also makes him a more difficult target to block. When facing a lead block head up in the hole he must attack the blocker from underneath, stand him up, and then shed and make the tackle. If he is facing a blocker on an outside run he has to make sure the blocker does not get his head across his body, then he has to "rip" through the blockers outside shoulder.

The second most important linebacker in the 4-3 defense is the strong side linebacker, also called the "SAM". The strong side linebacker plays on the outside and he is responsible for lining up to the side of the offense that contains the most blockers. This is often determined by where the tight end, fullback, or slot receiver is lined up.

In most 4-3 defenses the strong side linebacker has four primary responsibilities. His first responsibility is to head off any runs in the "D gap" and force them back inside. The second responsibility is to jam the tight end and keep him from cracking back on the "MIKE backer" on an inside run. The third responsibility is to cover the tight end and keep him from catching passes in the middle of the field. His fourth responsibility is to backside contain and guard against the reverse or misdirection.

The other outside linebacker of the 4-3 is the weak side linebacker or the "WILL linebacker. Like the "SAM" on the other side, he must guard the "D GAP" in a base defense. If the offense uses a two tight end formation then he will play over the tight end on the weak side and assume the same responsibilities as a "SAM" linebacker.

More often than not the "WILL" linebacker is a speedy backer that is frequently asked to blitz the quarterbacks on his blind side. Because of this the weak side backer will see screen passes thrown his direction than a strong side backer would.

He is also expected to protect the back side of the defense from misdirection plays. To do this he will key off of the guard to his side and the nearest running back. Many times he will trail a pulling guard from the back side in order to stop a reverse or end around for a substantial loss.

t should be noted that in the Chiefs 4-3 defense, Coach Cunningham does not differentiate between the strong and weak side linebackers. There is a right outside linebacker and a left outside linebacker, both are expected to do the same job.

In the 3-4 the left inside linebacker is also called the "MIKE linebacker". He closely resembles his counterpart in the 4-3 except that he aligns himself in a "two technique" over the guard to the tight end side. The right inside linebacker, referred to as the "MAC Linebacker" also aligns himself in a "two 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 ran in the NFL 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.

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. Both the "SAM" and "WILL" of the 3-4 will usually have "D gap" responsibility and will line up anywhere from a "7 technique" to a "9 technique".

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.

The Deceptive Face Of The 3-4
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.

The 3-4 is also particularly quick moving laterally. This was a primary reason why we have seen teams in the AFC West switch to the 3-4 defense in recent years, they had no answer for the stretch plays of the Kansas City Chiefs. The idea was to become light footed with additional linebackers in order to cut off the edges of the field on a more consistent basis.

Its 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 four seasons, 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.

So how do you stop such a versatile and unpredictable monster? Well, if you watched the Chiefs play the Ravens on Monday Night Football in 2004 there is your answer. Chiefs offensive coordinator Al Saunders put on a clinic that night on how to run right over the top of a 3-4. Control the nose guard and block down on the inside linebackers with your guards. For what the 3-4 has in quickness and deception it also gives up in bulk and power.

The Solid 4-3
The 4-3 is based on disrupting things in the middle with physical play and attacking from the edges with speed. It is traditionally a very aggressive defense and over the years its general philosophy changed very little.

In the 4-3 you tend to see more man-to-man defense than zone assignments. It is also obvious that the defensive line takes a much more active role in pursuing the run and rushing the passer. "Line stunts" on the defensive line are another mainstay of the 4-3. "Line stunts" are designed defensive plays where defensive linemen cross and loop over one another in order to break free from offensive linemen.

If done correctly the 4-3 is also very strong against the run. The defensive ends and outside linebackers are supposed to pinch things to the inside for the defensive tackles, middle linebacker, and strong safety to clean up. The two defensive tackles also make it much more difficult for the offensive line to reach the "MIKE" backer.

Though the 4-3 is much more predictable than the 3-4 it is also more balanced against the run and the pass. For that reason you will continue to see the 4-3 remain as the more common defense throughout the NFL. However, fundamentally neither defense is better or worse. You play to the strengths of your personnel and the weaknesses of your opponent.

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