Basic Defensive Coverages Series: Cover 3


We’re continuing our look at basic defensive coverage schemes and how the Buffalo Bills have used them. These are 101-level introductions that just begin to hint at the schematic complexity NFL defenses employ against the best offenses in the league, but they’ll give you a leg up in trying to understand why a defensive back was in a particular part of the field or why that linebacker ended up covering a wide receiver.

Our third coverage scheme is Cover 3. We’ll break it down below, but let’s start with how the Bills utilize it.

Bills’ Usage

According to Sports Info Solutions, the Bills used Cover 3 against 114 pass attempts, which ranked 27th in number of attempts. The Bills’ defensive statistics (and ranks) when using Cover 3 against pass attempts are pictured below. This number from SIS may differ from what you might find elsewhere because it’s based on whether or not there was a pass attempt. For instance, if the offense used a running play while Buffalo had set up in Cover 3, it would not show up here.

Stat (Rank)

Cover 3 Zones

Cover 3 is a balanced scheme, meaning the defense is not overly susceptible to either the pass or run. Cover 3 brings eight men into the box and has some exploitable weaknesses against the pass, mainly in the seam and versus four deep routes, but with solid execution those weaknesses can be covered. Defenders must communicate, be on a string with each other (especially underneath), and the deep third defenders have to keep receivers in front. There are also some variations that can disguise or create variables for Cover 3 to make it more effective against the pass, which we get to later.

Cover 3 divides the field into zones just like Cover 2 for the underneath zones, so the Swing, Flat, Out, Curl, and Hook zones are exactly the same. How Cover 3 differs is in how the deep portion of the field is divided. Simple enough, Cover 3 divides the field at 15+ yards into three equal areas, left, middle, and right.

Bills’ Most Important Players (not named Josh Allen) Entering 2023: #8 Gabe Davis


We continue to look at responsibilities based on the offense using 11 personnel (1 RB, 1 TE) and the defense using a 4-2-5 nickel, which is what the Bills use an overwhelming majority of the time (at least so far – that could change with Sean McDermott taking over defensive play calling and the departure of Tremaine Edmunds).

Safeties – Cover 3 is a middle-of-the-field closed (MOFC) defense because the Free Safety is closing off the deep middle with his location 15-20 yards downfield between the hash marks. The FS takes the deep middle third zone. Similar to Cover 2, he wants to be deeper than the deepest receiver, keep the play in front of him for as long as possible, and watch the QB’s eyes and motion. The Strong Safety is rotating up into the box to both help with the run and become an underneath zone defender.

Cornerbacks – Each wide corner has an outside third of the deep section of the field. Most likely, they started in an off position so they can drop back to their zone quicker. Playing off can become an easy indicator though, and CBs will need to vary their approach. They begin by back peddling into their deep zone. They maintain outside leverage, keep their eyes on the QB, and prepare to help close on an underneath completion to the out.

Since the CBs have a deep third, the SS and Nickel CB have to be prepared to carry the No. 2 receivers on their respective sides to prevent the deep CB from being flooded. The SS and NC can help prevent that situation in the first place by disrupting the No. 2 as he begins his route. If a receiver comes into the flat on their side, the SS and NC have to widen, play from high to low, and read/close/tackle.

Nickel CB – The NC has the Curl/Flat on the weak side, similar to the SS on the other side. The NC can help disrupt the timing of routes as they move into their zone.

Linebackers – The LBs will read for the run first, watching the guards for a high hat/low hat read. If the G drops, low hat, they prepare to play the run. If the G pops up, high hat, indicating pass, he drops back into the Hook/Curl area and just outside the hash. The LBs have to get enough depth to make it difficult to complete an in-breaking route behind them and be ready to read, close, and tackle on shallow routes in front of them.

At this point, you’ve noticed that the out zones are not completely covered. The outs are essentially vacated until the SS or NC is forced to go with a receiver into those zones.

Defensive Line – four-man rush

Bills’ Most Important Players (not named Josh Allen) Entering 2023: #9 Dalton Kincaid



In Cloud, the CB to the strong side takes the Curl/Flat instead of the deep third, which is then covered by the SS.


Buzz operates the same as standard Cover 3 except for the zones the SS and MLB take. In buzz, when the SS rotates up, instead of taking the Curl/Flat, he takes the Hook/Curl. The MLB widens to take the Curl/Flat. The coverage remains the same, but the rotation is different, presenting a different post-snap read to the QB and receivers.

You see below that Buzz is interesting because it can present like Cover 2, especially if the CBs start out playing closer to the line of scrimmage. The SS’s rotation then creates different plusses and minuses for the QB’s read of the scheme, forcing him to adjust on the fly post-snap. Even that small bit of adjustment can create enough time for the play to break apart for the offense.


Man Match

To this point, the zone coverages we have talked about are considered spot drop zones, basically meaning drop into a certain spot and cover it. Man Match or Pattern Match is a step up in complexity because it calls for the defenders to recognize the way routes are typically combined and use that knowledge to shrink their responsibilities. For example, if the TE runs into the flat, it’s unlikely that the X would run a shallow curl because they would be bunched too close together. Cover 1’s own Ant Prohaska describes it like this:

“Match coverage starts out as a zone based coverage, but based on a defense’s rules, can turn into man coverage once the routes distribute. For instance if a nickel corner has the first to the flat, and the No. 2 WR goes to the flat, the nickel takes him. And if the No. 2 WR turns his flat route into a wheel, the nickel stays with him and takes him”


Cover 3 is a well-balanced scheme that requires defenders to communicate effectively and know their defensive rules in order to prevent offenses from taking advantage of their weaknesses.

Next week, Cover 4.

You can find Chris on Twitter (@lowbuffa), getting dirty in #MafiaGardens, or watching football. Go Bills!