Cover 4 is a popular secondary coverage scheme employed by teams in the NFL, College, and at the High School ranks. In the Pac-10 during the 2007 it was played extensively by Arizona State, Washington State, and UCLA as a base defense. Other teams switch into it for a few plays a game as well. Here is one pre-snap example from the USC game versus Washington State in 2007.
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As the name implies cover 4 employs four deep defensive backs that can be aligned either four across OR aligned in something closer to a Cover 2 Shell. Often it is difficult to tell the difference pre-snap and can only be determined post-snap by the movement of the safeties. In basic Cover 2 coverage the safeties play 12 yards deep and normally step backwards upon the snap of the ball. After back or soft pedaling for two steps they read the offensive line and WR release they determine if the play is run or pass and react accordingly. Extreme emphasis is placed upon not getting beaten deep on the post patterns or corner patterns to their respective area.
In cover 4 however although the alignment may appear the same pre-snap there are some subtle differences. Normally the safeties line up closer to 10 yards deep instead of twelve and play down field toward the line of scrimmage more aggressively at the snap of the ball. Instead of retreating or soft pedaling two steps the safeties play flat foot and come forward at the snap of the ball (see images below). This difference helps to get nine men in the box more quickly versus run plays and yet still enables time to get four defenders deep on pass plays. When multiple WR's release down field past the initial seven or eight yard area cover 4 becomes essentially a man coverage scheme in the deep part of the field.
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The other big difference between cover 2 and cover 4 is the role of the corners. In pure zone cover 2 the cornerbacks stay low and defend the flats in their realm of responsibility. In press coverage they bump the WR's as they release and hand them off to the deeper safeties on the play while the corners play the shorter routes and watch for backs releasing into their area. In cover 4 the corners normally have responsibility for the WR's they align with and stay with them on deep routes. There are rules however that govern cover 4 (or any pattern read scheme) for that matter when there are releases by multiple WR's. As the graphic below shows in general form the DB's read the #2 receiver to their side and make adjustments accordingly.
Cover 4 Rules / Quarters Coverage
Cover 4 Strengths
In general every coverage scheme has relative strengths and weaknesses. Here I will attempt to summarize some of the more general ones pertaining to this scheme. For interested parties I'll listed sources and places to go for additional information at the conclusion.
- Cover 4 is effective in putting nine men in the box on run plays more quickly when the safeties read run on the play.
- The relatively low across positioning of the four defensive backs in the 10 yard range allows for excellent alignments to rotate to most any other type of zone or man coverage.
- The base look or cover 4 is similar to cover 2 and can confuse QB's on per-snap reads.
- The four across alignment of the defense provides a body in each deep quarter of the field.
- On plays where only one WR to each
side releases deep the defense can effectively double deep balls or
play some type of bracket coverage technique.
- On plays where 3 or 4 WR's release
deep vertically the defense can still put a body on each of the
defenders.
Cover 4 Weaknesses
- Cover 4 gives up underneath throws especially to the outside flat zone areas (see diagram below).
- The coverage allows outside throws such as the quick
hitch, screen play, or quick out routes, etc. by the WR's
- Corners can be beaten with excellent route running WR's that can execute double moves and get past the defender.
- Safeties that overly bite on play action are pulled up too far and routes can sometimes get behind them.
- High low reads on the secondary defenders can be employed by putting a WR in front of them and one behind to force coverage decisions.
- Screen plays and hitch plays to the outside can be
effective and gain big yards after catch if the initial tackle is not
made
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Further information
For further information beyond the superficial aspects presented here I'll list the main sources I used for the above information in case anyone would like to follow up for futher study.
The book Attacking Coverages with the Passing Game by former Pac-10 offensive coordinator Steve Axman does a nice job of outlining the basic types of secondary coverage that exist in football. The types covered include the four main zone coverages such as cover 2, cover 3, cover 4 (quarters coverage), and quarter-quarter-half coverage. The four man-to-man coverages are man-free (cover 1), cover two man under, four-across man, and blitz-man. In addition to explaining each scheme he outlines the strengths and weaknesses and best ways to attack each type. 39 different ways to attack cover 4 are described in schematic detail and the relative strengths and weaknesses are outline for each type of route concept.
This video by Mike Yeager Assistant Coach / Safeties coach at Indiana University depicts the base rules for playing cover 4 in their style of defense. The Indiana emphasis is still providing support on post routes to the middle of the field.
This video by Gary DeLoach former Assistant Coach / Safeties coach at UCLA depicts the base rules for playing cover 4 in their style of defense. Additional changes to cover three and cover two are depicted as well. The UCLA emphasis is more aimed at stopping the run by bringing down the safeties to help in run support.
This video by former Green Bay Packers coach Bob Valesente covers the base rules for playing cover 4 in their style of defense. In addition it covers the different adjustments required versus different formations and personnel groups. Special attention is given to covering 3 WR Trip Sets and adustments.
