The Argument for a Light Box

How a modern defense is using a light box & a two-high shell to manipulate the offense.

The offensive side of the ball tends to be more forward-thinking and less rigid in terms of trying new things. So it is not surprising that the embracing of modern analytics on that side of the ball has been quick to take hold. Most coaches understand that passing is a much more efficient way of moving the ball down the field (yes, this comes with caveats, but this is not the article for that). The offense has now made RPOs and reading static pre-snap coverages into a science allowing them to attack every inch of the field. In turn, the modern defense has to attempt to cover more space with fewer resources.

At the NFL level, 2018 is the year that broke football. The Eagles had just won a Super Bowl on the back of a back-up QB and “college” like plays. 2018 would see the explosion of the LA Rams offense, ascending of Patrick Mahomes (remember the 54-51 matchup?), and the option offense of Lamar and the Ravens. Defenses were put on notice and offenses started to shift towards early-down passing, play-action, and the use of RPOs. The Spread had finally taken hold of the NFL.

With NFL teams now running RPOs and manipulating coverages like never before, points are aplenty. NFL defenses are struggling to figure out how to manage the risk of packing the box versus giving up fatal shots. High-powered offenses like Kansas City, the Rams, and Green Bay manipulate coverages with motion and alignments, constantly seeking a mismatch (or creating ones).

Outside of RPOs, the growth of the Crossing route in the NFL has challenged the pre-snap alignment of many NFL teams. According to Seth Galina of PFF, 60% of passing snaps over the past six seasons have come against a single-high structure. This makes sense as the league (and defensive football in general) is focused on stopping the run. To do that, a defense stuffs the box and is generally in a single-high structure.

So how have offenses adjusted to the high usage of single-high coverages? Run deep crossing routes. These routes are great against Zone or man because the WR is running across the field either away from their man or into a window opposite the targeted defender. Versus single-high, the deep safety cannot assist with the crossing route because he has to protect the middle of the field from deep. Usually, a Post is complemented with the crossing route to hold the Safety high in coverage. The intermediate space is the sweet spot in every offense (i.e. high percentage throws)

In fact, according to PFF data, 76% of crossing routes are thrown against single-high defenses. Since the NFL, and many of the top college leagues, are dominated by single-high coverage it is no surprise that offenses have adapted. Opponents are eventually going to get good at what they have to combat. It’s simple evolution. NFL defenses now have to counter this onslaught at what was seen as a “stable” solution to stopping the run on early downs.

One trend on the defensive side of the ball has been the use of a two-high shell to “attract” the offense to run. Now, as most people understand, two-high Quarters has been used for decades to stop high-powered passing attacks, and static alignments (and coverages) in the modern game will get you torched. This shift in the attack by modern offenses has forced defensive coaches around the country, and at all levels, to change the way they think about defending modern offenses. The answer isn’t simply “Two-High Quarters.”

An example from the NFL has been the Fangio system which features a two-high shell with a three-down front. What this defense does, in particular, is leverage the fatal shot and give the offense the illusion of a light box. Different than a true four-down, the Fangio system uses five rushers to create man blocking situations and a two-high shell to invite the run, and it’s not even close as NFL Research shows (below).

This does not mean the Rams and Broncos are running Quarters on every down. In fact, the Rams utilize a variety of coverages to counter the offense. This is what gives the two-high shell an advantage over single-high. There is a natural layering effect in a two-high system that cannot be matched in a single-high scheme. This is not to say that defenses need to run Quarters. That coverage has its own set of issues, but the illusion of a light box with pre-snap alignments eliminating “gift” reads for RPOs can force offenses into less efficient plays.

The use of Wide-Zone from condensed sets has also led to more teams running a two-high shell. Add in the use of pre-snap quick motions (Jet/Fly) and it is only natural that teams are shifting away from a single-high look. Regardless of post-snap coverage, a two-high alignment allows the defense to shift easier with any motions. Wide Zone is best ran from under center. Utilizing a two-high shell allows the defense to change the picture post-snap when the QB has his back to the defense (play-action). Once the QB returns his eyes to the field, the defense can look completely different.

Along with Wide Zone, the prevalence of play-action Deep Crossing routes combined with play-action has been used to attack single-high looks. Again, these can be negated through various two-high alignments and post-snap rotations. For instance, in a single-high system, the Deep Cross can gain easy access to the other hash. The defenses Seam player is down near the box in a single-high coverage and more susceptible to play-action.

In a two-high scheme, the Seam player can play from the “table” or from depth. So even if he triggers on a run read, he is sinking into the area of the Cross and can leverage the route from the opposite side of the field (think of it as a head start). This slight adjustment can pay dividends versus this popular concept of Wide Zone play-action featuring a Deep Cross.

As stated, in a two-high system, the defense can sink for depth into the area being attacked by a Deep Cross. Depth leverages the defender versus the Crossing route. This can be done running various forms of Quarters or Cover 1 or 3. In the single-high world, this is known as 1/3 Cross or Lurk. This layering effect can be done from either side of the aisle (Quarters or Single-High). The advantage is in alignment, not scheme. Below is an example by the Rams.

Tampa Bay runs a play-action Deep Cross against what appears to be Quarters coverage. The Safety to the TE will trigger on the run read and pop back out once he identifies pass. This puts him in the area of the Deep Cross. To the top, the Safety stays high and “cones” or doubles the Post with the opposite CB. This is the layer effect that a two-high system can have.

Below is another example from a two-high shell versus Seattle. This time the rotation is weak.

One of the best examples of a forward-thinking defense in the NFL is the aforementioned Rams (DC Brandon Staley is a Fangio disciple). As Next Gen Stats shows below, LA is #1 in showing a light box at 85% of the time. As of Week 11, they were the only defense to not give up a deep TD and were tied with Pittsburgh for the most interceptions on deep balls. Entering Week 12 the Rams were 8th in DVOA according to Football Outsiders and 12th in Run DVOA. Not bad for a “two-high system.”

Again, and I cannot stress this enough, being a two-high system does not mean you don’t run single-high coverages. This is a philosophy that I have talked about multiple times as a known “Quarters Guy.” Living in two-high alignment is a defensive philosophy, not a rigid scheme. In anything, if you are static and only do one thing you are going to get fetched.

Modern offenses have too many tools and answers to static coverage regardless of scheme. There are “beaters” for everything, so the main idea is to keep the offense guessing through slight change-ups that create doubt. What I have termed, Cautious Aggression. Now the question is, how do you stop the run from a light box?

Analytically, running is less efficient than passing. Defensive coaches must understand this. That is not to say that run fits don’t matter, or offenses should only pass. Saying that would be dense and missing the point. If the defense is reactionary and offenses are now primed to read and react to pre-snap looks, why not force the offense to run?

This is what I argued in my last conversation with Chris Vasseur on his Make Defense Great Again podcast. Since the offense is seeking space, why not give them the illusion of it (or lack of it) to manipulate the reads. Or simply, force the offense into a less efficient play by alignment. Force them to run.

The Rams utilize a mixture of five and four-man fronts with their two-shell looks. The five-man front creates one-on-one matchups with their D-line and EDGE players. Staley (DC) uses a mixture of Bear (303) and Under schemes to change the leverage. The use of “flex” players on the edges allows the Rams to keep a two-high shell and “steal” gaps inside.

An example of this is shown below. The away-side EDGE can fold in and take the Safety’s gap. This is taking four-down Quarters principles and hybridizing them in a three-down alignment.

When running their Nickel package, the Rams use their EDGEs to wall and contain outside runs, or to stunt them inside to steal gaps. Another way Staley uses a light box to his advantage is the use of line movement and pressures from the second level. This has been a common theme in modern four-down Quarters football. To steal gaps, the defense needs to move players to “waste” the O-line.

Below the Rams run a pressure away from the TE and RB. The line will move and read the next O-linemen as they cross-face. This movement plus the addition of a second-level defender destroys the blocking scheme. The static Quarters alignment is unassuming and the inside leverage of the Nickel makes it impossible for the WR to block him.

With the NFL using condensed formations, quick motions, and running more Wide Zone with crossing routes it is not surprising that two-high alignments are becoming more prevalent. The main defensive family that is using the alignment to their advantage is the Fangio system. This doesn’t mean that they are running solely Quarters. As most DCs understand, static alignments and coverages will get you beat. Everyone has beaters.

Single-high coverage still dominates the league, but Staley and the Rams (and the Broncos) are using a two-high alignment to play with the pre-snap box reads of the offense. The two-high alignments also allow the defense to layer the crossing routes that dominate offensive schemes. This looks like a trend to keep an eye on.

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