The secondary is the name given to the group of players on an American football team who make up the defensive backfield. All the players who make up the secondary are called defensive backs, but that category is further divided. In a nutshell, these players are responsible for preventing the opponent’s receivers from catching the ball. If they fail, they must then make the tackle, preventing a possible touchdown. The different players work in slightly different ways.
The cornerback is typically the fastest of the defensive backs. The ideal NFL cornerback can run the 40-yard dash in 4.4 seconds, weighs between 180 and 190 pounds, and is at least 6 feet tall. However, the average NFL cornerback is about 5’10”. Although speed and agility remain the necessary commodities, height is becoming a factor in order to defend the ever-increasing height of today’s wide receivers.
Here’s the cornerback’s role in two specific types of coverage:
Cornerbacks in man-to-man coverage: Most defensive schemes employ two cornerbacks (CB) in man-to-man coverage against the offense’s wide receivers (WR).
The cornerbacks align on the far left and right sides of the line of scrimmage, at least 10 to 12 yards from their nearest teammate (usually a linebacker or defensive end) and opposite the offense’s wide receivers. The distance varies depending on where the offensive receivers align themselves. Cornerbacks must align in front of them.
Most teams attempt to place their best cornerbacks against the opposition’s best receivers. Some offensive formations place a team’s two best receivers on the same side of the field, requiring the defense to place both of its cornerbacks accordingly, as shown in this figure.
Cornerbacks in zone coverage: If a team’s cornerbacks are smaller and slower than its opponent’s receivers, that team usually plays more zone coverages, fearing that fast receivers will expose its secondary’s athletic weaknesses. However, if you have two talented cornerbacks, your team can play more man-to-man coverage.
Most defenses employ two safeties — a strong safety and a free safety. They must see and recognize the offense’s formations and instruct their teammates to make whatever coverage adjustments are necessary:
Strong safety: Of the two types of safeties, the strong safety is generally bigger, stronger, and slower. Coaches often refer to (and judge) their safeties as small linebackers. These players should
Be above-average tacklers
Have the ability to backpedal and quickly retreat in order to cover a specified area to defend the pass (which is called dropping into pass coverage)
The strong safety normally aligns to the tight end side of the offensive formation (also known as the strong side, hence the name strong safety), and 99 percent of the time, his pass coverage responsibility is either the tight end or a running back who leaves the backfield.
Free safety: Generally more athletic and less physical than the strong safety. He usually positions himself 12 to 15 yards deep and off the line of scrimmage.
The free safety needs the following traits:
The speed to prevent a long touchdown pass.
The speed and quickness to get a jump on any long pass that’s thrown in the gaps on the field.
The capacity to make instant and astute judgments. Some people say that an excellent free safety can read the quarterback’s eyes, meaning he knows where the quarterback is looking to throw the football.
Able to cover a wide receiver in man-to-man coverage.
Nickel backs and dime backs
Some experts try to equate learning the nickel and dime defensive schemes with learning to speak Japanese. Not so! All it’s about is making change. When defensive coaches believe that the offense plans to throw the football, they replace bigger and slower linebackers with defensive backs. By substituting defensive backs for linebackers, defensive coaches ensure that faster players — who are more capable of running with receivers and making an interception — are on the field.
Nickel back: The fifth defensive back to enter the game (five players equal five cents).
Dime back: The sixth defensive back to enter is termed the dime back. The dime back position received its name because, in essence, two nickel backs are on the field at once. And, as you well know, two nickels equal a dime.
The one downside of using a defensive scheme that includes nickel and dime backs is that you weaken your defense against the running game. For instance, many modern offenses opt to run the ball in what appear to be obvious passing situations because they believe that their powerful running backs have a size and strength advantage over the smaller defensive backs after the ball carrier breaks the line of scrimmage.
The following figure shows a common nickel/dime alignment that has a good success rate against the pass, especially when offenses are stuck in third-and-20 situations. This alignment enables teams to use many different defensive looks, which help to confuse the quarterback. But this scheme is poor against the run, so the defense has to remain alert to the possibility that the offense will fake a pass and run the ball instead.