A scramble in football is when the quarterback leaves the pocket to avoid being tackled. A scramble, unlike a rollout, is not by design. Quarterbacks are often forced to scramble when their receivers are unable to create separation and get open for a pass, at which point the quarterback will sprint away from where the ball was initially received in an effort to buy time or run towards the first down marker.
Although scrambling outside the pocket is not ideal, some quarterbacks are inept at avoiding defenders and gaining yards when forced to scramble. Quarterbacks such as Russell Wilson, Patrick Mahomes, Cam Newton and Lamar Jackson are generally considered good scramblers, using their foot speed to run for first downs or elude defenders until a receiver becomes open.
Blitzes from the defense often force a quarterback to scramble to prevent from being tackled behind the line of scrimmage. Blitzing occurs when the defense sends extra players after the quarterback by having them rush past the line of scrimmage when the ball is snapped rather than drop back into coverage. When this happens, the offensive line often becomes overwhelmed due to the fact that there not enough blockers to hold off the excess pass rush. As a result, there are several defenders converging on the quarterback within a matter of seconds, creating the need to escape the pocket and avoid the opposition.