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Defense by Diaco

Introducing the defensive philosophy of new UConn head coach Bob Diaco.

Matt Cashore-USA TODAY Sports

The single question that looms highest above all others after any significant hire in sports is always the same.

"Is this the dawn of a new, successful era?"

That inquiry, of course, can never truly be answered until many years have passed and everyone's favorite 20/20 hindsight goggles are available. However, with the hiring of former Notre Dame defensive coordinator Bob Diaco, we can say for certain that this is a new era for the UConn defense.

Success? Well, we'll still have to wait and see on that.

In the meantime, the Huskies have without question entered into a new time of gap control, linebacker playmaking and flexibility. All of these characteristics are hallmarks of the two-gap, 3-4 defensive system Diaco has coached the last eight years and now carried with him to Storrs. He learned to teach this style under former Virginia head coach Al Groh, who owns a branch of the Belichick-Parcells coaching tree from his time coaching the 3-4 for the New York Giants in the 1980s.

Below, you'll find a concise breakdown of the system and its principles. For a much more technical and extensive review, read up on what our friends at One Foot Down had to say on their former coordinator's defense nearly two years ago. You can also see a Notre Dame-heavy primer at

Otherwise, welcome to defense by Diaco.


(picture courtesy of

Defensive Line: DE, NT, DE

This is where it all starts.

The most basic assignment for the three down linemen is to ocupy blockers and allow the four linebackers behind them to make plays. Typically, three-on-five is a battle no one should ever want to fight. Yet, every 3-4 lineman is expected to weigh-in at around 290-300 pounds (over 300 for the nose guard/tackle) and to use his size to take over multiple "gaps" between offensive linemen.

The nose guard (NG) here is responsible for controlling both "A" gaps (on either side of the center) and occupying either space in case of a run to that area, even in the likely event of a double-team. To his right and left are the defensive ends, who are supposed to do the same for the B and C gaps in front of them. They will typically grab a hold of the offensive tackle across the line of scrimmage, stand their ground, peer into the backfield for where the play is headed and then move into that given space.


(picture courtesy of

If these three fail in executing their assignments, offensive linemen are then free to take on the four, smaller linebackers. As you'll recall, these linebackers are the focal point of playmaking in this defense. Should they be unable to fend off free blockers, this unit is in trouble.

Linebackers: Cat, Will, Mike, Dog

While the names of the linebacking positions in this defense could just as well form an unfortunate Nickelodeon show remake, they're actually much more purposeful. The "Cat" and "Dog" spots stand for the outside linebacker positions, where the primary responsibilities include pass rushing, "holding the edge" against perimeter runs and pass coverage. Between the two, the "Dog" linebacker is expected to perform the more versatile role given he will often line up across a tight end, meaning he could drop into pass coverage or have to stay in against the run at any time. When an opposing offense goes to a three or four-wide receiver he, the "Dog" will almost always be lifted for an extra defensive back.

On the opposite side, the "Cat" linebacker seemingly acts as a fourth defensive lineman. He is frequently called upon to rush the passer and must be able to hold up one-on-one against offensive tackles. In an ideal two-gap, 3-4 defense, the player at this position should lead his team in sacks.

Sandwiched between the pair are the inside linebackers, Mike and Will. The "Mike" is known as the quarterback of the defense, as he relays the playcalls and make proper adjustments pre-snap. The "Will" inside linebacker will always align himself to the weakside of an offensive formation. Both players must be very instinctual, given their responsibilities on every play are to first diagnose whether they're facing run or pass and then immediately react to guard the interior of the defense against either attack.

Secondary: FC, BC, FS, SS

The biggest difference between the two cornerback positions in this system (there are more) is in alignment. The FC or "field cornerback" will always man the widest side of the field on a given play, and the BC or "boundary corner" will cover the short side. The FC typically is the superior of the two cover men, though the BC should find himself in many one-on-one situations. The free and strong safeties play similar roles to those you'll find in most other defensive systems.

As a whole, this defense usually plays a lot of zone coverage. In 2013, UConn was almost exclusively a Cover-1 and Cover-4 team, with about a 50-50 split between man and zone. Going forward, you should expect a heavier dose of zone  thanks to higher number of Cover 2 and Cover 3 calls and some zone blitzes mixed in.


When executed properly, this is one of the most difficult defenses in football to sustain long drives against.

Proof lies not only in the statistics, but the fact that Diaco rode this system and the talent of his Notre Dame defenders to the 2012 assistant coach of the year award. However, you'll recall that 2012 did not end so well for the Irish as a team. They were bludgeoned 42-14 by Alabama in the national championship, which drove head coach Brian Kelly to call upon one Bill Belichick to examine his program top to bottom.

After a few days spent in South Bend, it turns out that one of Belichick's most noted takeaways was that the defensive coaches needed to instruct and allow their players to make adjustments against what opposing offenses were doing pre-snap. Simply, the defense was too static.

Whether or not Diaco was successful in implementing that change this season hasn't fully been determined. The Irish did suffer a drop in their defensive performance this season, though some of that can certainly be credited to injuries and the coaches did alter their approach.

For now, it doesn't matter.

The fiery, 40-year old Diaco has arrived with years of quality experience, advice and preparation that were provided in part by Super Bowl champions. And while it will be his new face that leads UConn into a changed era of football, it shall be an old, tried and true defense behind him that gets the job done.

(Of note: It may be a year or two before we see this system's full implementation.The techniques and principles within Diaco's schemes are different from what any current Husky defensive player has been taught thus far in his career. The smartest, newly hired coaches adapt their playbooks to best take advantage of their current personnel's strengths, before recruiting the ideal players to execute their systems.)