49ers: A Defense in the Mold of a Rival, Part 2 — The Cover 3 and Cover 1 Pass Defense

In part one of this series on the 49ers defense, we looked at the base seven-man fronts the 49ers can be expected to use. Today we’ll look at the base passing defenses. Today we’ll look at the cover 3 and cover 1 pass defenses.


In part one of this series, we covered the base 4-3 fronts fans can expect to see this coming season.

As the 49ers continue to build their defensive scheme in the mold of the 2012/2013 Seahawks, one thing fans can expect to see from the pass defense is the cover 3 and cover 1 defenses, a significant departure from the primarily cover 2 defense employed in the past.

Cover 3 is most basic pass defense at levels of football.



In cover 3, the outside corners and the free safety drop into coverages that divide the field into thirds, with the underneath linebackers dropping to the middle and flats to take away the intermediate passes. The strong safety either is there to play the run or take away a passing lane.

This is the Seahawks’ nickel Cover 3 alignment versus the 49ers’ 11 personnel (3WR-1TE-1RB):

(All coverage and assignment diagrams adapted from Bleacher Report’s Matt Bowen)

Cover 3 is also the defense that NFL quarterbacks have the easiest time carving up, so one way to mitigate this is with a modified pattern-match coverage on the outside.

In this Seahawks scheme, the corners will usually play press coverage and run with the receivers if they run straight down field. If the receivers don’t run streaks, the corners will still bail to their deep third assignments down the side lines.

The outermost interior defenders, usually the strong safety and the opposite outside linebacker or nickel defender in the case of the above diagram, will drop to the curl zone (sink into the throwing lane) or, according to Matt Bowen, “buzz through the curl to the flat and widen with the flat receiver or running back.”

The middle defenders, the inside linebackers (MIKE and WILL) will look for run or pass by reading the blocking sets of the interior of the offensive line and if a pass set, will sink into a middle hook zone outside the hashes at a depth of anywhere between seven to 12 yards.

The linebackers are watching for any hash seam route but must also be able to drive on any underneath crossing route.

The free safety will roam the middle of the field and only gain enough depth to create a pursuit angle to drive on a post, dig, or crossing route.

(All coverage and assignment diagrams adapted from Bleacher Report’s Matt Bowen)



One variation of the cover 3 is the cover 3 “buzz.”

This pre-snap look of the defense looks closer to a cover 2 defense with the strong safety closer to cover 2 depth.

(All coverage and assignment diagrams adapted from Bleacher Report’s Matt Bowen)

Instead, the strong safety will fill in for the hook zone defender normally in that space.

This allows the linebacker on that side, the SAM normally, to drop into the curl and buzz the flat is the ball heads that way.

(All coverage and assignment diagrams adapted from Bleacher Report’s Matt Bowen)

The strong safety will break on the ball from his position on any pass that comes his way.

The corners will funnel the outside receivers in with outside leverage.


In Cover 1, the outside defensive backs play press man coverage or off-man coverage, both with outside leverage meaning shaded to the outside of the receiver’s shoulder or his outside eye.

Per Dave Archibald at Inside the Pylon:

Cover 1 defenses tend to be aggressive, with just one deep defender. They can be vulnerable to big plays if the free safety lacks range or if the cornerbacks and linebackers cannot provide tight man coverage.

(Adapted from Matt Bowen’s Cover 1)

Corners can line up in “off-man” coverage 7-9 yards off the receiver, allowing the defensive back to sit and read the quick three-step passing game route concepts. It allows the defender to stay square and drive on the hitch, slant, curl, etc.

Corners can also play press with an inside leverage when the receiver is in a “plus split” (2-3 yards outside the numbers, ball on the opposite hash) that allows them to take away any in-breaking routes and also use the sideline as help on any deep or deep comeback routes.

The underneath man coverage defensive backs or linebackers will use an outside leverage technique to try and funnel the receivers into the middle of the field.

The WILL and SAM linebackers will man-up on the running back(s) and will “green dog” the rush with a delayed blitz or rush to cover and read the quarterback if the running back(s) stays to pass block.

The MIKE linebacker will drop underneath to the second level, allowing the free safety to cover the deep middle of the field and is free to roam where the deep pass goes.

(Adapted from Matt Bowen’s Cover 1)


Another variation of the cover 1 incorporates the “robber” coverage with the strong safety dropping into the underneath hole normally occupied by the MIKE linebacker, similar to the cover 3 buzz.

The defense usually does this from a cover 2 or 2-man pre-snap shell.

(Adapted from Matt Bowen’s Cover 1)

Instead of the MIKE linebacker dropping into the underneath middle, the strong safety will fill that void with a “robber” technique while the MIKE runs man-to-man with either a tight end or running back.

Seahawks safety Kam Chancellor is in perfect position to take away any underneath crossing route if the offense sends a receiver into his zone:

In the cover 3 or cover 1 defense, the most important player is the free safety. In a single high safety defense, the free safety needs to be able to erase the entire deep middle of the field. He needs to have the necessary range and ball skills as well as be able to identify the correct technique to take away deep route concepts.

Having this talent at the free safety position allows the underneath defensive backs to play the more aggressive, natural style defensive backs are known for knowing they have their field general behind them for clean-up.

Which is why 49ers fans should be very excited at the prospect of Ohio State free safety Malik Hooker being available with the No. 2 pick in the 2017 NFL Draft.

In any case, this should help you identify the basic pass defense coverages that are likely to be employed this coming season.

Any questions or comments, drop them in the comments section or find me on Twitter.

All images courtesy of NFL.com and NFL GamePass.