If you can read your defensive coverage in football, you have a good chance as quarterback of getting through the game with a clean jersey. Few excel more at the skill of the presnap read than Denver Broncos quarterback Peyton Manning, who takes very few sacks. Running backs and receivers, as well as linemen, also need to know what the defense is trying to achieve to make the most of each offensive play.
Study the position of the cornerbacks, the two defensive players who play widest and slightly dropped behind the line of scrimmage, if you are the quarterback or a receiver. If the corners are facing forward, they are in man-to-man coverage, and if they are facing toward the middle of the field, they are in a zone. For additional confirmation, look to whether the cornerback lines up outside of the wide receiver -- again indicating zone -- or inside, indicating man coverage.
Examine the position of the safeties, if you are a quarterback or receiver. The safeties typically cover the middle of the field and drop back 7 to 20 yards from the line of scrimmage in a deep zone. Look for a safety who runs up from the deep zone to encroach near to the line of scrimmage, indicating a blitz.
Continue to read the defense as it moves just before the snap and just after the snap, regardless of your position. Defenses try to camouflage their intent with last-second shifts in position. If you are a wide receiver, you will look for separation from a cornerback who is shadowing you in a man-to-man coverage. If after the snap the cornerback is watching the quarterback closely and backpedaling, you are facing a zone coverage and need to look for areas of the field where neither the cornerbacks, safeties or linebackers have clear responsibility, such as the deep post.
Know the number of players in the “box,” an imaginary rectangle between the tight ends on offense and the defense, including the farthest-back linebacker, if you are a running back or on the offensive line. If you are the quarterback, adjust your play calling to the availability of lanes for your running back to succeed in gaining yards.
Be prepared for the fake blitz, where a safety creeps up the line of scrimmage to indicate a blitz and then drops back to cover a deep pass before the snap.