A quarterback will sometimes call an audible after approaching the line of scrimmage and reading the defense. By calling an audible, they immediately change the selected play, allowing the offense to take advantage of mismatches. It�s also possible for the leader of the defense to call an audible, and the defending players will make their adjustments accordingly.
An example of an audible would be when the quarterback comes to the line after having called a running play in the huddle. He notices that the defense is preparing to blitz, so he yells out a special code which lets his teammates know that a different play is being run. This code might take the form of something like �Blue 42� or �Texas 29.� In this example, he might opt for a passing play and have the halfback stay in the backfield to pick up the blitz.
Often, a quarterback will call an audible from a run play to a pass play or a deep pass play to a shorter route, or vice verse.
Reading the Defense
If a running play is called and the defense is bunched at the line, the quarterback might take advantage of the man-coverage to throw the ball deep to the receiver. Or if the defense appears to be blitzing the quarterback, the passer might call a hot route which strikes quickly before the blitzers get to the quarterback. This is called a “hot read”, because the quarterback reads the defense and makes the necessary adjustment.
Peyton Manning is an example of a quarterback who will often call audibles at the line of scrimmage. He runs the Colts� offense out of the no-huddle, so he will often make adjustments at the line after he�s had a chance to look over the defensive formation. Manning�s success in the NFL demonstrates how effective the audible can be when utilized by a skilled quarterback.