Transitioning to a 3-4 defense?

Donatell's lengthy NFL career has largely focused on coaching defensive backs. He was the secondary coach with San Francisco from 2011 to 2014 under Jim Harbaugh, overlapping with both Vikings general manager Kwesi Adofo-Mensah and O'Connell there. Donatell also coached defensive backs with the Bears from 2015 to 2018.

He was on the Denver Broncos staff that won back-to-back Super Bowls in the 1997 and '98 seasons, and then became the defensive coordinator of the Packers from 2000 to 2003, followed by a three-year stint in the same role with the Falcons.

His schemes have long employed two-deep safety looks, and he figures to bring similar concepts to Minnesota at a time when teams across the league are shifting back to using two safeties in place of the single-high safety looks that the Seahawks popularized in the early 2010s.

In front of those defensive shells, Donatell could shift the Vikings to a 3-4 defense, after 16 years in a 4-3 base scheme under Mike Zimmer, Leslie Frazier and Brad Childress. Though Donatell coordinated a 4-3 scheme with the Packers and Falcons, the Broncos played a 3-4 with Donatell and Fangio. If the Vikings make such a shift, it could change their evaluation of pass rushers like Danielle Hunter and D.J. Wonnum. They could be well-positioned for a shift to a three-man front with defensive tackles like Michael Pierce and Dalvin Tomlinson, though the Vikings will have salary cap decisions to make with a number of players on their roster.

Strengths of the 3-4 Defense

The 3-4 is a flexible defense and provides some great advantages when it comes to rushing the quarterback and defending against the pass. Because there are only three linemen, the outside linebackers may play the role of the defensive end at some times, essentially giving a 4-3 look.

The 3-4 can be confusing for opposing quarterbacks, who may find it tough to keep track of these roving linebackers who line up all over the place.

Because it offers so many options and presents so many different looks for the opposing offense, many NFL teams have switched to the 3-4. This is probably largely due to the explosion of the passing game in recent years.

With its base personnel, the 3-4 is much more effective at dealing with intricate offensive game plans involving multiple-wide-receiver sets, tight ends who may line up anywhere, and versatile halfbacks capable of catching the ball downfield.

With the same personnel, a 3-4 defense might line up in a three-man front, a four-man front, or even a two or one-man front. It’s up to the opposing quarterback to figure out where everyone is, and what role they are playing. For a defense that is a huge advantage.

3-4 Defensive Weaknesses

Because of its flexibility, the 3-4 may seem like the ideal defense, but much of its success depends on having the right personnel at various positions. To effectively stop the running game a team will need a dominant nose tackle that is capable of occupying space and taking on several blockers without giving ground.

Defensive ends are not only expected to have the speed to rush the quarterback on passing downs but also to have the strength and size necessary to take on offensive linemen and keep them off the inside linebackers on running plays.

Outside linebackers need to be incredible athletes with a non-stop motor and a great nose for the ball. Inside linebackers need to have the toughness to take on offensive linemen, but also the speed and agility to cover backs out of the backfield.

As you can imagine, special players in these positions are not always easy to find, and a poor performer can hurt the whole defense. Without a dominant nose tackle, the 3-4 can be very weak against the run. Without linebackers who can both cover backs and tight ends and bring pressure against the quarterback, a team will suffer in passing situations.

Line Alignment & Gap Responsibility

Defenses align themselves based on the offensive line. Each lineman plays a different "technique," indexed off of the position of the offensive line:

Lining up directly across from the center, guard, tackle and tight end are the zero-, two-, four- and six-technique positions. Lining up in the gaps are the one-, three-, five-, seven- and nine-technique positions. Where you see an "i" in the alignment, that's lining up in between the offensive lineman's head and shoulder—in line with his eye.

The 3-4 Pass Rush

In a traditional 3-4, the nose tackle plays a "zero technique" and is responsible for covering both A gaps. The ends play a "four technique," and are each responsible for covering a B and C gap:

The prototypical 3-4 two-gap nose tackle is a 320-plus-pound widebody—a space eater who can take on a double-team and still stop a running back. This player is rarely expected to generate any kind of pass rush. The New England Patriots' Vince Wilfork is a great example.

3-4 defensive ends must be true two-way players, typically 280 pounds or more. Their prime responsibility is to stop the run, but they must also have the ability to beat offensive tackles and sack the quarterback. Few players can truly dominate in both roles, but Justin Smith of the San Francisco 49ers does.

The pass-rushing stars of the 3-4, though, are not the defensive linemen. The size and strength of the men up front allows the linebackers to attack any of the gaps with almost any number and combination of linebackers.

The best pure pass-rushing linebacker typically plays on the right (ROLB), attacking the blind side of the quarterback from the outside edge. The LOLB also brings heat on the strong side, but he may have to fight through a tight end, depending on the protection. DeMarcus Ware of the Dallas Cowboys and LaMarr Woodley of the Pittsburgh Steelers are two of the best 3-4 outside 'backers in the business.

The biggest threat the 3-4 poses to offenses, though, might be the two interior linebackers. Though they can help pick up the coverage slack left by the blitzing outside guys or blitz in combination with them, they can combine to execute one of the most difficult-to-stop blitzes in football: the Double A Gap Blitz.

If you remember the gaps above, you'll immediately understand what this is: the two inside linebackers both blitz up an A gap. Depending on what the nose tackle does and if the tailback is kept in to pass protect, the Double A Gap Blitz often results in a linebacker one-on-one with a tailback, a completely unblocked linebacker or even two unblocked blitzers.

The results can be devastating, as Dom Capers' Green Bay Packers demonstrated against the Patriots. When the nose tackle moves to the outside, drawing the right guard away, the two ILBs cross each other in front of the center, who can only block one of them. ILB Desmond Bishop is left free to deliver the sack.

3-4 Pass Rush Drawbacks

It's well known that a weakness of the 3-4 is the "world theory": There are only so many natural two-gap 3-4 nose tackles in the world, and if you don't have one you can't stop the run. To an extent, it's true of 3-4 DEs as well: not many ends can overpower tackles and tight ends in the run game yet still have the speed and technique needed to sack the quarterback.

Without quality ends, the pass rush must come from the blitz.

Relying on the four linebackers to provide the pass rush is a dangerous game. Linebackers must also share coverage responsibilities, and too-aggressive blitzing can be exploited by good quarterbacks.

Large, strong inside linebackers are crucial, as second-level blockers like tight ends, fullbacks and pulling guards are hard for two-gap linemen to occupy. ILBs must be able to shed these blocks quickly in order to make plays.

Looking back at the ‘20 season, Fangio and Staley ran similar schemes. Their use of a two-high shell made them outliers in an NFL dominated by middle-of-the-field closed defenses (MOFC); both the Rams and Broncos were over 80% two-high pre-snap usage! The pre-snap alignment of the Safeties is a trademark of the Fangio system and is used as a leveraging tool for defending modern offenses.



The Fangio system uses the Safeties depth to force offenses to run into a perceived light box. In LA, Staley leveraged his D-line talent to force offenses to win their matchups up front. As a result, the Rams would often only have one box LB on the field, creating the illusion of a six-man box.

As a result, teams consistently tried to run the ball and were stifled. The only better-run defense was the Buccaneers, who ran a similar front structure but focused on man coverage with a Post-Safety (Cover 1). The image below illustrates the philosophy Staley implemented to terrorize NFL offenses all season.



Fangio’s 2020 defensive campaign was not as stout as the Rams. Denver had injury issues from the beginning of the season as Von Miller missed the entire ‘20 campaign. In addition, moves at CB didn’t pan out, and the offense was abysmal. In short, the Broncos’ defense was “just OK.”

2021 looks different as Fangio made moves this offseason to bolster the CB position adding a familiar face in Kyle Fuller (Bears), another starting CB candidate in Ronald Darby (WFT), and drafting Patrick Surtain II (Alabama) in the 1st Round of the draft. Von Miller is back and should give the Broncos tremendous depth at D-line alongside Bradley Chubb (who can move inside) and Malik Reed. Inside, Shelby Harris and Dre’Mont Jones are both very good. At the Safety position, the Broncos finally resigned Kareem Jackson, who pairs with Justin Simmons and is arguably the best Safety duo in football.

Schematically, Fangio was trying to do similar concepts as Staley, but with less D-line capital. For the most part, Fangio opted to play defense against 11 pers. based offenses from his Nickel alignment (4-2). Fangio would take the Nose out and bring in a 3rd CB to play the Slot.

One thing that is noticeable in the Fangio system is the lack of premium placed on ILB play. The Rams arguably have one of the worst LB cores going into the 2020 season. Though Josey Jewell is serviceable for the Broncos, and Alexander Johnson can play in multiple spots, there are no elite players. The money is being spent in the backend and on the edges of the box.

The 5-1 box featured by the Rams was used by Fangio too, but it looked different because of personnel. As stated, Fangio was based mostly out of a 4-2. The Broncos would shift the Will down onto the line to look similar to Staley's Rams defense. In my language, I call this Over Walk (below). “Walk” tells the Will to align as a wide 5 tech. and the DE will shift to a 4i or 3 tech. The front is played with a Shade Nose.



To the weak side of the line, the O-line is leveraged by a defender. The only open gaps are to the front side. The alignment builds a natural wall for modern offenses that like to use the TE in an “off” position and pull him weak (Split Zone/Stretch). As illustrated, the Will can fold back inside versus a run away.

The fluidity of the LBs allows them to fit the ball and concentrate on the RB. To add numbers to the box, the Safety to the TE sinks down. Though the Broncos are in a 4-2-5 personnel, the defense can function similarly to Staley’s 5-1 system in LA.

The front structure is important, but the uniqueness of the Fangio system lies in how he manipulates the secondary post-snap. As noted, the Rams and Broncos were outliers in the two-high shell category. However, that does not mean they run a high volume of Quarters coverage associated with a two-high shell. Instead, Fangio uses the depth of the safeties to leverage the offenses of the NFL.

The two-high alignment can confuse QBs because they have no idea what the coverage structure will look like post-snap. There is no tell. With play-action usage on the rise, the scheme changes the picture as the QB turns to show the ball to the RB. When the QB snaps his eyes back to the secondary, the picture is completely different, and hesitation is death in the NFL.