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By Mike Kuchar Senior Research Manager X&O Labs [email protected]

"We didn’t want to tie the back-side safety into read side (trips side) and not help with single receiver," said Chuck Clemens. "It’s exactly what these offenses want you to do."

When teaching coverage to players, the install progression is becoming all too familiar with defensive coaches.  It’s the whole, part, whole theory.  First teach the entire coverage (whether by whiteboard or walk though), next break it down by position grouping and finally rep it on the field during seven-on-seven or team sessions.  Sure, it may simple but when offenses start to dictate personnel by changing formations, they’ve taken it to a whole other level.

No longer can defenses make a living staying in "country cover three" and one coverage against all formations.  Offenses are too sophisticated, and too well coached, for that. Most QB’s and coordinators will diagnose the voided areas within seconds (regardless of how well you disguise) and pepper your secondary with first downs.  It’s because of this that defenses have gone to more split coverage concepts – playing one half of the formation, or field, differently than the other.  Truth is, only 5.9% of the coaches we surveyed actually stay in the original coverage called.  The rest make their checks pre-snap based on personnel and formation.  So, while the offense may be dictating  coverage, most d-coordinators will argue they will have the last check and time to adjust by the time the ball is snapped.

Before we get into the most common coverage adjustments, it’s important to examine the "why" before the "how" as to playing split field coverage.  Based on our research, the coaches we spoke with check their coverage based on three potential variants:

  1. Unbalanced sets – 3x1 (trips) or 3x2 (empty)
  2. Personnel groupings, most usually based on tight end or no tight end personnel, for the threat of a consistent run game
  3. Field/Boundary tendencies
Based on our research, some of the more common split field coverage’s we found are:
  • Cover-four mixed with cover-two
  • Robber coverage mixed with cover-two
  • Robber coverage mixed with man
  • Man coverage mixed with quarters
The strong side of the defense can be predicated by field position (such as field or boundary) or by receiver strength – coaches call it both ways.  We’ve found that many of our coaches utilize their split field coverage concepts mainly against 3x1 or 3x2 formations.  Reason being is the myriad amounts of potential routes that offenses can sting you with. Quite simply, football is still a numbers game, and defenses need to account for offensive numbers. So if an offense comes out in an unbalanced offensive set (where there are more receivers on one side of the formation than the other) the defense needs to account for that.  Our researchers at X&O Labs found the most common checks defensive coordinators will make and how they teach their players to play them.

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Case 1: Split Coverage Checks Dictated By Unbalanced (3x1) Formations

Handling trips formations is always a cause for concern among defensive coaches.  In fact, 47.5% of coaches we surveyed are most concerned with the various route combinations from trips formations rather than aspects such as the skill of the back-side X receiver or the run ability of the QB or back.  Trips can be classified as any three eligible receivers to one side of the formation, which can or cannot include a tight end.  Over 41% of coaches that took part in our research use some sort of split field coverage to defend trips – mainly because it’s unbalanced by nature and offenses are stretching the field vertically with four possible immediate threats.

Assessing an opponent’s offensive personnel is imperative before devising a game plan and we all know that our adjustments can vary from week to week, but most coordinators have specific ways in which they will defend trips by nature.  Trips presents the immediate threat of four receivers going vertical at the snap of the ball into the four deep areas of the zone.  These same receivers can be employed to affect four potential horizontal areas in a zone.  Because of this, coordinators are no longer teaching spot drop zones in coverage.  Instead, they are teaching man principles to zone defenders by having them "lock" on once a defender enters their area of coverage.  This can be achieved through communication and recognition.

For example, Haskel Buff, the defensive coordinator at Fort Valley State University (D-II), defines anything vertical as clearing LB depth.  The Wildcats base their defenses out of the 4-2-5 scheme with a two-deep shell.  Buff plays with a four down front, two interior backers, three safeties and two corners.

What Buff does is play a split field coverage rotated to the trips formation where he’ll play some form of match-up cover-one to the trips and what he calls a read quarters scheme back-side (Diagram 1).   The corner to the side of the trips is in press man alignment and will handle #1 regardless of route.  Note:  In our research, we’ve found that the number one receiver to the trips side gets the ball the least of the three.  The strong safety plays five yards off the ball on the outside tip of the number two strong receiver while the free safety plays between number two and three depending on their splits.  "We’ll have that free safety keying two to one," says Buff.  "If number two is down (not vertical or inside) he helps on number one with the corner.  If number two is vertical he plays him.  The strong safety will travel with anything to the flat, but it’s the Rover, or back-side safety, that can get caught in a bind."

In a true quarters scheme, the Rover will help the corner by robbing any under cuts or any vertical routes, but Buff ties the Rover into coverage on the front side.  But because that Rover is at 10 yards depth in the weak side B gap, his run fit becomes compromised.   "We give him a ball key post snap, which is the back in the backfield.  If there is no threat of speed option his way, he can scan the field to the trips side.  Now he reads three to two to one on the trips side.  If three is vertical and across he plays him.  If three is out to look to number two on the vertical and if number two is not vertical, check to see if number one is coming across the field.  At least from his depth at 10 yards, it may be easier to play.  Essentially we lock that corner on number one with inside leverage.  He can’t expect help."

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Of course, knowing the true talent of that single receiver (X) away from the trips side can cause some adjustments.  Most offenses will align their most dominate threat to that side in order to gain an advantage on an isolation route.  It’s something that defensive line coach Chuck Clemens at Central Missouri State has been dealing with his entire career as a defensive coach.   Which is why Clemens plays what he calls "special" (Diagram 2) which gives immediate assistance to the single isolated corner on the X receiver.  Clemens would lock the trips side corner on number one and have the strong safety (or what he calls the read side linebacker) and free safety play a cover two principle on the number two and three receivers to the front side of trips.  This would allow the back-side safety (or rover) to help on number one with the back-side corner.  "We didn’t want to tie the back-side safety into read side (trips side) and not help with single receiver," said Clemens. "It’s exactly what these offenses want you to do."

Case 2: Split Coverage Checks Dictated By Field Position Instead of basing coverage on formations, other coaches we spoke with predicate their coverage on field position.  Over 15% of coaches dictate their coverage strength to the field side.  It’s something that Jared Pospisil, the defensive coordinator at Union High School (IA) has been doing for the last three years he’s been there.  Pospisil runs an over 4-3 scheme but double calls his coverage mainly on field position.  He used to play pure quarters, or cover 8, which is the most commonly used coverage structure for 4-3 teams, but found he needed to do something to handle speed mismatches in the secondary.  "I don’t have the ‘good-enough’ athletes anymore to play straight four across in the back end," said Pospisil.  "If there is a slot out wider than usual, I had a hard time telling that safety to his side to watch both run and pass."

So what he does now is call most of his coverage to the field, which incidentally, is where most offenses place their better receivers.  He’ll have his players make a "box" call to any double width sets – where the safety to the field side can get stretched vertically (Diagram 3).  It’s essentially a Tampa Cover two principle to the field and a quarters principle to the boundary.  The corner to the field side will line up one yard outside #1 and six yards deep while the strong safety to his side (Pospisil puts the strong safety to passing strength) will be 12-14 yards deep depending on down and distance.  Both players read the EMLOS (end man on line of scrimmage) for run or pass reads.    For Pospisil, everything that occurs post-snap is predicated on the eyes of the quarterback.  "If the strong safety reads the QB eyes towards him he will weave with the QB’s shoulders and get off the hash.  We will always drive off the QB’s off hand.  If #2 or #3 runs to the flat, the corner comes off and plays him.  The strong safety will stay on the hash until the QB makes him come off."  With any threat of #3 vertical, the Mike has the vertical carry.  "It’s a tough read for a box player, but we just tell our Mike to get deep enough where the QB has to put air under the ball.  He might be a step behind number three and that’s okay but he still has to turn and run once he diagnoses pass."

Researchers’ Note: You are reading the summary version of this Research Report. To access the full version of this report – including the corresponding Statistical Analysis Report featuring the raw coaching data from our research – please CLICK HERE.

Concluding Report

We’ve found that split field coverage can be effective in handling all the route combinations that spread teams can hurt you with.  It doesn’t matter how you call the coverage – 56% of coaches we surveyed called it by phrases and the other 44% called it by numbers.  Whatever the case, the key to be effective is communication in the secondary and knowing your personnel.  If you decide to play split coverage, safeties, corners and linebackers are not interchangeable.  You’ll have to decipher who your better cover players and put them in the right spot to make plays.  Each side of your defense, from center line, is working separately – getting the coverage mixed up can account for big plays and scores. Copyright 2011 – X&O Labs



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