Cover 3 Zone
Type of coverage: three deep, zone underneath coverage with an inverted safety (safety covering an underneath zone)
Strengths: Three deep secondary, strong side run support, safety covering the strong side flat, safety as force man to the strong side run.
Weaknesses: Weakside flat, flood routes, curl zone to the strong side, dig (square in) routes, weakside run support.
Indicators: This coverage is usually associated with eight man fronts and is one of the most preferred coverage’s in run situations because a safety is in the box as the force (contain) man on a strong side run. The first indicator is the safety in the middle of the field and he will be lined up deeper than both cornerbacks. That said, teams will rarely give away the coverage that easily. Chad Henne must use a post snap read to pick this coverage up. The cornerbacks will usually have large cushions (usually 8 to 10 yards) covering the deep zones to each side of the safety. Teams will disguise this coverage in a variety of ways. One common way is lining up in a cover 2 look and then walking down the safety (almost always the strong safety) close to line. He usually gets 4 to 6 yards from the line so he can be in position to cover the strong side flat. The positioning is too critical for the safety to stay in a cover 2 look at the snap and effectively cover his zone, so scanning for the creeping safety is an indicator.
This coverage is tricky for a young quarterback because it can be made to look like a cover 1 or cover 2 prior to the snap. The free safety in the middle of the field is the same concept in both cover 1 and cover 3. The read then goes to the corners, who will usually have a more aggressive position in cover 1 because there is no inside help (unless the strong safety plays bandit coverage and covers the medium range middle zone).
As if this defense wasn't hard enough to detect, another thing defenses like to do is to have the strong side cornerback cover the curl zone and have the two safeties combine with the weak side cornerback to cover the deep three zones. Again, the key in this read is post snap, which is when all these defensive changes take place.
How to attack this coverage:
Given Michigan's west coast style passing game, the quick out route is key against the cover three zone because it is a low risk pass against a deep cushioned cornerback. The key for Chad Henne is getting his throwing target correct and getting the ball to the receiver in a catchable manner. At times last year Henne threw balls too high and it made it harder for his receivers to catch and run smoothly. Henne has one of the strongest arms in all of football, so getting the ball out to his receivers is not the issue. Consistently throwing a more catchable ball on the short out routes is the key.
Another common attack is the post route. It goes across the cornerback covering his deep third, behind the linebackers dropping into their zones, and in front of the free safety. If the receiver can find the soft area of the zone that I just mentioned and the quarterback makes a good throw, this is an effective pass with big play potential. Examples of these routes are in the image below.
There are number of other patterns that can also be effective against the Cover 3. The square in route (ran by the weak side split end receiver in the image below) is effective in getting into the zone between the linebackers and deep cover cornerbacks. A pass to a back in the flat is also a good method of attack because it gets the ball to a playmaker in space. It's an even better option on the weak side where the linebacker has to come and support against the running back swing pass. It is most effective when a curl or inside route is run and drags the cornerback and weak side linebacker to the top of their zones, thus increasing the room that tailback has to operate. Another thing to monitor is the depth in which the linebackers drop, Michigan loves the quick hitch routes against a deep dropping zone. The curl route to either side by the receivers is also a nice cover 3 buster. It again exposes the void between the underneath and deep zones. Examples are of these routes are shown below.