Flexibility through flexing
Since his Super Bowl days in Denver, Mike Shanahan has been an advocate of flexing running backs into and out of receiver sets as a good way to exploit formation matchups and force defenses to tip off coverages. This is especially true near the goal line, where a defense keying on a running back will have to adjust quickly if the back flexes wide.
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2 At the snap, the running back stays at the line of scrimmage as the hot read, while the two left-side receivers run routes that take the trio of defenders out of the middle of the field. The quarterback’s play fake to the left side takes the weak-side linebacker completely out of the play, and the strong-side receiver’s fade route eliminates the man-press cornerback to that side. Now, the tight end, who ran a quick route to get open right at the goal line, beats the strong-side linebacker, and gets underneath the strong safety. After the play fake to the left, the quarterback fired the ball in for the touchdown.
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1 The offense lines up in a three-receiver set, with a tight-twins look on the left side and the tight end in line. Before the snap, the halfback motions outside the twins receivers, taking the right cornerback outside and indicating man coverage in the red zone. The cornerback motion sets a triangle of defensive backs against the three-receiver set to the left, and the weak-side linebacker flexes out as well.