4-2-5 Study: Case 3 – Formation Adjustments and Split Field Coverages

Mar 9, 2016 | Front, Even Front Structures, Defense

The 4-2-5 Study: Case 3

Formation Adjustments and Split Field Coverages

By Mike Kuchar

Senior Research Manager

X&O Labs

Researchers' Note:  Before reading any further a simple clarification must be made.  When referring to the 4-2-5 defense, we are referring to the PERSONNEL on the field, NOT the structure.  The 4-2-5 defense consists of four defensive lineman, two linebackers, two cornerbacks and three safeties.  Below you will see some examples of two-safety defenses, one-safety defenses and no-safety defenses, which we’ve found could be employed by using 4-2-5 personnel. 

Like most defensive structures, there are a myriad amount of coverage’s that a coordinator can play behind it, but we’ve found that to be successful coaches must subscribe to the "less in more" theory - get good at a doing a few things right (or playing only a few coverage’s).   Typically speaking, those that consistently use the 4-2-5 structure implement the following coverage’s on a weekly basis.  Because these coverage’s independently can be the subject of its own special report, we’ve decided just to give a brief overview and description of each before going into more depth later in the report.


Robber Coverage



Split safety coverage where both sides of the coverage relies on a "cheat half" principle by the corner, who will play a half-field principle.  The strong safety plays number two to the flat while the free safety handles number two vertical and "robs" the threat of number one on a curl route.   This is known as Cover 2 in Virginia Tech’s system.


  • With the addition of the Free Safety, the ability to place up to nine defenders in the box against the run game.
  • Direct support to the strong side flat with the presence of the strong safety.
  • Good against short passing game such as the strong side hook to curl area because of the presence of the free safety.
  • Excellent adjustment vs. Trey (Pro Trips) or Trio (Trips Open)


  • Cornerbacks can be left one-on-one on an island with wide receivers.
  • Weak side of coverage is vulnerable to flat area because strong safety is opposite.
  • Vulnerable against double width (two wide sets) because of strong safety is opposite, weak side inside linebacker will need to have coverage responsibilities (which we detail later).

Base Rules:

  • CBs: Play a "cheat halves" technique to your side. Our research found that 79 percent of coaches play their corners 1x7 (one yard inside, seven yards off) of the number one receiver.   They will be responsible for any deep post or vertical route of number one.  On the snap, flip hips to middle of the field and get on hash.  In in some systems we found, this player will play more of read principle and will handle the out route of any number two receiver, this includes the "wheel route" which 45.1 percent of the coaches we surveyed agreed that it was the best way to play it.  This will be detailed later in the report.
  • Strong Safety: This player will play the flat responsibility or "swing deep of number three" meaning the out route of the number three receiver.  Our studies have shown that the majority of coaches (42.4 percent) align this player 4x4 (four yards outside and four yards deep) off the tight end.  Although some coaches train this player to handle ALL flat routes, in some coverages we found, he has his corner handle any flat breaking routes of number two with his strong safety playing all flat breaking routes of three.
  • Weak Safety: This player will be responsible for the flat area if there are two backs in the backfield and no number two to his side.  If there is a number two to his side, most coaches will lock this safety man-to-man on number two, which can be a glaring weakness in this coverage.
  • Free Safety: In "Robber Coverage" this player will handle the threat of number two vertical.  If he doesn’t have number two vertical, he helps the corner "rob" number one.  We’ve found that the majority of coaches choose to have him line up "inside the frame" of the number two receiver and play 10 yards deep.
  • Strong side LB: This inside backer is the linebacker to the Robber side or the "read side" of coverage.  His job primarily is to match the vertical threat of number three and becomes the middle dropper.
  • Weak Side LB: This insider backer is the linebacker to the weak side or the "away side" of coverage.  His job primarily is to match the vertical threat of number two, which can be an instant problem area in coverage, particularly in the play-action game.

To see the actual teach tape that Virginia Tech uses to install Robber coverages against various formations, click on the link below.


Video 1: