Cover-0 (also known as Zero-Man) is a coverage designed to pressure the quarterback and cover with the minimum number of defensive backs. As the defense is relying on the pass-rush to disrupt timing, it is a risky play-call and is generally reserved for red-zone usage.
The eight box players will show pressure to force max-protect. Linebackers use a "green dog" technique on the two inside eligible receivers (man coverage, add to the rush if assignment blocks). Rushing the QB off the snap will force the ball to come out.
Corners will play "Solo" technique (i.e. man-coverage with no help). Corners align head-up, will drive the up-field shoulder on a
slant and play through the receiver's hands on a fade. No need to play the double-move, if the pressure doesn't get home, this play is sunk.
Some defenses prefer to "press" their corners in order to interfere with the timing between QB and receiver.
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