Editing Cornerback (section)

==Jamming the receiver==
[[File:Charles Woodson and Randy Moss - San Francisco vs Green Bay 2012.jpg|thumb|[[Green Bay Packers]] cornerback [[Charles Woodson]] (21) covering [[San Francisco 49ers]] wide receiver [[Randy Moss]] (84). ]]

When a cornerback is attempting to jam a receiver, he is trying to disrupt the receiver's route at the line of scrimmage. Many routes are precisely coordinated between the quarterback and the receiver, to the point that a quarterback may throw the ball without looking, knowing his receiver will be in an exact spot after a certain time. Jamming will disrupt the timing between the two, which provides the defense with extra time to sack the quarterback (sometimes called a "coverage sack"), or force an ill-timed throw that misses the target. In addition, a proper jam allows the safety or linebacker to provide stronger run support because he then has more time to drop back into zone coverage in the event of a pass. In other words, he has been granted more time by the corner to recover from his mistakes if he anticipates a run when in fact the play is a pass.

Proper jamming technique requires the cornerback to use their legs, shoulder width apart. At the same time, the cornerback thrusts their arms forward into the receiver's chest to maximize power. When properly executed, a jam can knock a receiver off his feet. Jamming is only legal within five yards from the line of scrimmage.

If the jam fails, the cornerback is usually flat footed and not in a suitable position to defend the mid to long-range passes. When this occurs, the safeties and [[linebackers]] usually cannot return to their zone obligations in time, especially if they were anticipating a run as the play began. In essence, the defense is unnecessarily "stretched" to its breaking point.  Receivers who can effectively avoid the jam and stretch defenses are far more likely to create big play opportunities for the offense. Therefore, it is vital that a cornerback execute a proper funnel or jam to allow safeties and linebackers enough time to return to their zone responsibilities in the event of an unforeseen pass play. By working together and familiarizing where one's help may come from, a higher degree of confidence is established among the defensive secondary as a unit, with the result translating into a much more formidable defense against both the run and pass.