As coaches we get older and often forget that the players we coach remain the same age. With this in mind, it is often good to revisit your learning roots to make sure that everyone is on the same learning curve. If you have not read my blog FIELD LAYOUT you may want to give it a quick read before continuing with this concept.
As a player I was fortunate to have a coach take the time to teach me the basics of field structure and how defenses use zone coverage to protect them. This blog post will focus on how a quarterback can see the defense's zone structure and it will better explain and understand how we attack these concepts through the passsing game.
The concepts are mostly generic but it does have an emphasis to the Canadian game. The larger field helps to get a better understanding. The field is 65 yards wide and is a great space to attack with a spread offense if your quarterback has a strong enough arm.
From the offenses side of view we look at the defensive zone in LEVELS and SEAMS. Together they form a grid of possibilities for any offense and a challenge to the defense to cover.
Lets start with LEVELS. There are traditionally 3 levels in a defensive zone (discuss a fourth concept later), from the LOS of scrimmage (LOS) to the toes of the underneath defenders defining the Level 1. For example, when the linebackers recognize that it is a pass play they drop off to cover their assigned zone. From the tip of their toes back to the LOS is considered LEVEL 1 and it stretches across the field to include the Depth of the lowest defender to the Field and the Boundary. For now this is a basic definition of the concepts and a more in depth blog describing the possible variables will follow.
Jumping to LEVEL 3 - this is the area behind the deepest defender. The long bomb, the big play that every defense wants to avoid. Typically these is from the heels of the safety and other defenders that are covering the deep zones.
These mentioned levels create LEVEL 2. The area left over is from the heels of the Level 1 defenders to the toes of those deep defenders.
Now that we understand how the field is divided vertically we should evaluate how it is divided horizontailly and those are the SEAMS. The Levels are actegorized by numbers and the Seams are labelled by letters. Starting from the sidelines in.
Key note to remember - there is always one more seam than defender.
In a cover 3 deep concept, the defense can use a variety of players to get 3 defenders back to cover Level 3. As they drop back to protect against the "home run shot" They position themselves inside their zones and this creates the seams.
Level One is often occupied by more defenders because the quarterback has an easier throw and the ball can get to the receivers sooner. The time that the ball is in the air and the time it takes the defender to get there is called "Delta T" (key concept for any quarterback to understand) and will be its own blog topic in the near future.
If the five Level 1 defenders covering from sideline to sideline are spaced evenly then the 6 seams would be almost 11 yards wide. These seams will also be reffered to as Windows.
The underneath seams extend into Level 2 as the routes develop but for an easier understanding the image to the right displays the 5 underneath defenders that create the 6 seams for the offense to attack. The ongoing joke is that a quaterback only needs to be able to count to 12 to read defenses. Not quite true but a good start. With a four man rush, the QB already knows that there are 8 defenders in coverage.
Earlier I mentioned a fourth level that has evolved with defensive philosophies. That is LEVEL ZERO. This level is the area of the field that the defense has decided not to cover because of down and distance. Rather than worry about a short throw completed for less yards than needed the underneath defense will deepen their drop to minimze LEVEL 2 and "rally" to the ball when it is dropped underneath.
The game is ever changing but this is a good introduction to build off of.