Cover 3 is a basic coverage that most teams have in their defensive playbook. For the most part, it is fairly standard in the alignment and assignments of the DBs. The field is divided into thirds, with the two corners responsible for the deepest man in the outside 1/3s and the free safety responsible for the deepest man in the middle 1/3. The strong safety will drop down to the "curl/flat" zone to the passing strength of the formation. The curl/flat zone is actually two of the underneath zones being covered by one player. The passing strength is determined by the number of eligible receivers on that side of the ball, and the receivers are numbered from the outside to the inside-- 1, 2, 3 etc. The three linebackers are responsible for the other underneath zones. The three linebackers and the strong safety work together forming a net of coverage underneath the 3 deep defenders, passing off receivers to each other as they cross into other zones. In this coverage, we have four defenders to handle the six underneath zones, so good quarterbacks will be able to complete passes on shorter throws in holes between the zones. But, the idea in zone coverage is that all of the defenders are watching the quarterback and should be breaking on the ball to be there for big hits and quick tackles on any completions. When QBs read this defense, they are supposed to attack the outside because it is the weakest area of the defense. Usually in Cover 3, you will see a lot of out routes and comebacks on the outside because the middle of the field is covered by the underneath "droppers" and the free safety in the deep middle zone. Corners will generally line up at 7-8 yards off the ball so they can see the entire formation. Sometimes our dbs will show "press" (and line up close) at the line of scrimmage and then bail out late, so the QBs do not know we are in cover 3.
Fire zone 3
Most of the time when we see Stanford in cover 3, it is when we are zone blitzing. These blitzes are often called "fire zones." In a fire zone, we lose one of the four underneath droppers, whether it be a safety, corner, or linebacker on the blitz, but we gain a fifth pass rusher. Fire zones create bigger holes for the QB to throw to, but the idea is that he has less time to make good decisions with the football. The ball should come out fast, so the DBs should be able to play tighter in coverage and anticipate the quick throw. This is where reading the three-step drop of the QB becomes very important. Every player in the zone should be reading the drop of the QB and planting and driving to the ball as he starts his throwing motion. We tend to see Stanford in this defense on third and long and other obvious passing situations.
This is really our base coverage. More often than not, when we aren't blitzing, we are lining up in cover 4. Cover 4 is normally some form of quarters coverage. There are many different ways to play cover 4. Our defense plays cover 4 like a zone, but with man-to-man principles. We line up with our corners pressed at the line of scrimmage and they cover their WR man-to-man on any route, except for a shallow crossing route that goes underneath the linebackers. The linebackers will pick up this shallow route when they see it crossing underneath them. The safeties line up about 9-10 yards deep and read the line of scrimmage to see if it is a run or a pass. It is very important they read the linemen instead of the QB and running backs, because while the skill position guys can sell a fake, linemen cannot block downfield on play-action passes, as they would on run plays. If the safeties read run, they are flying up into the box, creating a nine-man front. This is part of the reason why our safeties rack up a lot of tackles in our defense. They are rarely accounted for in offensive blocking schemes. In this defense, the safeties are the "force" player against the run. If the safeties read pass, they turn to their pass responsibilities. The strong safety is lined up over the No. 2 receiver, usually a tight end in two WR sets, and is responsible for him on basically any route that goes deeper than the linebackers. The strong side linebacker should help make the safety's job easier by getting a jam on the tight end or No. 2 receiver to slow him down as he releases down the field. The free safety is responsible for the No. 3 receiver if there is one, but a lot of the time he will end up being a free player in this coverage. As a free player his job is to read the quarterback's eyes and try to "steal" routes. A good free safety should be able to read route combinations and make plays in this defense. Also, a good free safety can give corners inside help on passes like digs, curls, and posts.
The linebackers are dropping into the underneath zones, similar to their roles in the cover 3 defense. They also will match up with receivers in their zones as if it were man, but usually they are taught to stay back and use their body positioning to help the back 4 in their coverage. When I played under Coach Shafer, we also did a lot of blitzing out of this coverage. It doesn't hurt too much to lose the extra linebacker in coverage because the DBs are basically playing man coverage on the receivers. So there shouldn't be any true holes in the defense. I like this defense because it allows corners to play tight man-to-man coverage, but they are not totally on an island because they could possibly receive help from both safeties as well as have linebackers dropping into zones underneath them. Although they may receive help from their safeties, corners must play as if they are on their own. You never know what route the safety is going to get, and whether or not they will be there to help.
Cover 2 is another standard coverage that nearly every team uses. Stanford will use cover 2 as a change of pace from cover 4, because both coverages look the same before the snap. We also tend to use this defense when we don't want to give up a quick score. We play this coverage out of both nickel and base personnel. In cover 2, the corners will line up anywhere from pressed at the line of scrimmage to about five yards off the ball. Their main job is to get a jam on the receiver and "re-route" him, to slow his release down the field. This makes the safety's job much easier. After the corner jams his receiver, he is responsible for the short outside area of the zone known as the "flat." In this defense, the corner is usually taught not to jump the flat route but to sink back underneath deep routes to make a smaller window between him and the safety over the top. Cover 2 is a fun defense to play for corners because there is a chance to make some big hits on tight ends and running backs releasing into the flat as they rarely expect you to be there. Also, the corners are first in run support in this defense because the safeties are too deep to have much effect on the run game. So, the corners are the "force" players in cover 2. The safeties will generally line up 10-12 yards deep and back pedal at the snap to get to their pass responsibilities. The safeties divide the field into two halves and are each responsible for the deepest man in their half of the field. When quarterbacks see two safeties deep, they are taught to attack the middle of the field. Generally, teams will run the outside receivers deep down the field to widen the safeties and try to hit a slot receiver or tight end down the middle of the field. This is why it is so important for the corners to slow down the outside receivers with a good jam and then sink underneath them, so the safeties don't have to expand too wide, leaving a big hole in the middle of the field. This is also why some teams will send the middle linebacker deep into the middle of the field, in what they usually call "Tampa 2." The other area opposing teams will try to attack is the soft spot between the corner and the safety. Another reason why corners are taught to sink back underneath deeper routes is to make this a tough throw over the corner's head but in front of the safety. The linebackers drop into their usual short zones, but they have a lot less ground to cover because the 2 corners are also playing underneath coverage. The corners are covering the flat routes, so the outside linebackers will drop into the hook/curl zones and the middle linebacker will drop straight back into the middle. The strongside linebacker, or "Sam" will also jam the No. 2 receiver or the tight end as he releases down the field, to make it easier on the safety. There should not be a lot of room to throw the ball underneath, as there are five defenders to play the six underneath zones. This is another coverage we usually see at the end of the half or the end of the game when we have the lead, or if the opponent is in obvious passing situations.
Another change-up we see from the Stanford defense from time to time is what I am going to call cover 6. This defense has many different names depending on who is running the defense. Basically, it is a combination of cover 4 and cover 2. The strong safety and the corner on his side are playing cover 4, while the free safety and the other corner are playing cover 2. (Thus, the name cover 6.) On the strong side, the corner will play man to man unless his receiver runs a shallow crossing route, in that case the linebackers will pick him up. The strong safety will read the offensive line to see if it is run or pass. On a run play, he will fly up to the line of scrimmage in run support, and if it is a pass, he will look to the #2 receiver or the tight end and cover him if he releases down the field. On the weakside, the corner will jam the receiver and attempt to slow his release down the field. Then he will sink back and cover the flat. The free safety will drop into his half of the field and play the deep zone over the top of everything on his half of the field. This defense can trick a quarterback and cause him to make mistakes because the defense is in two different coverages. Also, it can confuse tight ends and wide receivers in their blocking responsibilities in the run game, because on one side the corner is the force player and on the other side the strong safety is coming down hard against the run. This was our base coverage back in 2005 when Coach Tom Hayes was our defensive coordinator. This is a good coverage, but it requires more communication between the corners, safeties and linebackers so that everyone knows what side of the defense is in what coverage.
While it may still be hard for us as fans to know exactly what coverage we are in while watching the bowl game, these are the major coverages that we can look forward to seeing our Stanford defense in against Oklahoma in the Sun Bowl.
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