Summer of Spags: Introducing Amoeba fronts

When Steve Spagnuolo was hired during the 2019 offseason, there were many questions about what he (and his all-star assistant coaches) would bring to the Kansas City Chiefs defense.

So here at Arrowhead Pride, we penned the Summer of Spags series, detailing coverages, blitzes and tendencies we had seen on teams Spagnuolo had previously coached, creating a crash course for fans (and Ant Man) about what they could expect to see from the Chiefs defense in 2019.

Fast-forward to the present. Spagnuolo has led a massive defensive turnaround, holding up his end of the deal opposite a high-octane offense. Throughout the year, the Chiefs defense grew by leaps and bounds, implementing many of the techniques and tendencies we had seen on tape.

Most Chiefs fans trust that the Chiefs defense is in good hands and will continue to build on its stellar close to the 2019 season — especially since the team won’t need to learn a completely new playbook.

For the defense, this offseason is about growth. With the foundation now in place, Spagnuolo and his staff can add new wrinkles and implement even more exotic formations, pressure packages and coverages to keep opposing offenses off-balance.

So Summer of Spags now returns. We’ll look at some concepts that Spagnuolo could implement in 2020 — whether through suggestions from his assistant coaches or examples he saw on film — to try to expand on his already-diverse defensive playbook.

The concept: Amoeba fronts

Defensive coaches use Amoeba fronts as a way to play an unpredictable “positionless” box. The goal is to make the front as fluid as possible and set it in motion during the pre-snap process — thereby confusing the quarterback (and offensive blockers) on obvious passing downs.

Chiefs defensive line coach Brendan Daly is familiar with the implementation of these fronts; during his time there. the New England Patriots experimented with them.

In these clips from 2018, head coach Bill Belichick and defensive coordinator Brian Flores utilized a single defensive lineman, a combination of three EDGE/linebackers, a dime linebacker/safety, and six defensive backs. By sacrificing a little heft along the defensive line in obvious passing downs, the defense put more speed and superior blitzers on the field.

Adding speed and better rushers isn’t an exotic concept. The wrinkle is introduced when you make them fluid in their coverage drops and rushes. While only a single player has their hand in the dirt, the linebackers and safeties in the box move pre-snap to different gaps to show pressure or coverage — and can then switch a moment later. This unpredictability leaves the offensive line unsure not only where the rushers are coming from. but how many are coming.

This unpredictability creates hesitation within the offense, because the offense’s blocking rules change based on the number of rushers and the gaps to which they are aligned. So by repeatedly changing the looks pre-snap, you stress the communication throughout the line, adding an extra split second to the blockers’ processing. That extra split second can allow a free rusher on a stunt due to a late rotation, penetration on the interior through a lineman who is trying to sort out his assignment — or even a completely unblocked blitzer.

There are a couple of elements required to make amoeba fronts work. The defense has to have linebackers or EDGE defenders capable of effectively rushing and dropping into coverage. A rigid, heavy defensive end isn’t a convincing coverage defender. Likewise, a 225-pound finesse linebacker on the defensive line is not a likely pass-rushing threat. So to make amoeba fronts work, two-way players are a necessity.

The other key element to make amoeba fronts effective is a set of solid man-coverage cornerbacks and safeties.

These plays show the defense crowding the box, leaving the boundary cornerbacks on islands with little over-the-top help. Even when the defense can get a safety deep, it’s typically a late rotation. The defensive coordinator has to trust his cornerbacks to carry vertically on the outside.

There is also a natural hole that can appear in the defense because the hook defenders — if there are any — have a lot of ground to cover when they drop into intermediate zones. When aligning near the line of scrimmage, the three to five extra yards safeties and linebackers have to cover can leave space for in-breaking routes. This means that the cornerbacks and safeties in man coverage have to be sticky throughout the route tree — lest they give up easy separation in the holes left behind.

How it fits the Chiefs

Spagnuolo is already accustomed to playing light dime/quarter defenses on obvious passing situations, so implementing this wrinkle shouldn’t be a difficult ask. When they feel comfortable, Daly lets his rushers play from a two-point stance, so it’s also not out of the question for his defensive ends to widen and play standing up.

The personnel needed for these looks is not far removed from what the Chiefs currently have. Chris Jones would be the first, best candidate to offer an interior rush with his hand in the dirt. Frank Clark and Alex Okafor are both comfortable rushing from a two-point stance or dropping into coverage, offering some unpredictability off the edges. Spagnuolo has sung the praises of 2020 draft pick Mike Danna for his coverage drops — and we’ve seen the Chiefs utilize Tanoh Kpassagnon in coverage as well. Up front, they definitely have the horses to make this work.

At the second level, the Chiefs could also be in good shape. These fronts need strong blitzing linebackers with good lateral agility. The Chiefs have two of those in Damien Wilson and 2020 draft pick Willie Gay Jr. In 2019, Spagnuolo felt comfortable taking Anthony Hitchens off the field in these obvious passing situations, so it’s not out of the question that he could do it again.

Finally, the Chiefs will need three safeties they can count on — and a slot cornerback who can blitz well. We know that Tyrann Mathieu is a dynamic chess piece — and that Juan Thornhill has the range to show a Cover 0 blitz and then drop to cover the deep middle of the field. Daniel Sorensen makes sense in a dime linebacker role that is similar to how the Chiefs have recently used him.

But when they went to their dime defenses in 2019, the Chiefs used Rashad Fenton in the slot cornerback role — and using the second-year player as a man-cover corner in these situations could be a big ask. Similar concerns may arise on the outside, as the typical safety help Spagnuolo offered Charvarius Ward and Bashaud Breeland over the top would be missing.

Amoeba fronts would not be concept Spagnuolo would trot out every week — but it fits nicely in his current pressure packages. If Chiefs cornerbacks can take the next step — offering a little more man coverage on the back end when unprotected — the team definitely has the horses up front to create some dynamic amoebic fronts as a “curveball” in 2020.