The offensive line in American football is made up of five players, with the man in the middle called the center. Every offensive line position is based on the center. To the right of him is the right guard, and outside the right guard is the right tackle. To the left of the center is the left guard, and outside the left guard is the left tackle.
The following figure helps you see the positioning of the offensive line's personnel.
If the quarterback is right-handed, the left tackle is also referred to as the blind-side tackle. Why? Well, a right-handed quarterback generally drops back to pass and turns his head to the right while doing so. He can't see behind him, so his left side is his blind side.
The following sections give some generalities about the players at the three main offensive line positions — center, guard, and tackle.
Centers
Like a center in basketball, a football center is in the middle of the action. He's the player who snaps (or delivers) the ball to the quarterback. As the snapper, he must know the signal count — when the quarterback wants the ball to be snapped, indicated by a series of commands, such as "Down. Set. Hut hut hut!"
This center-quarterback exchange initiates every offensive play. Before the play begins, the center stands over the ball and then bends down, usually placing both hands around the front tip of the football. He snaps (or hikes) the ball between his legs to the quarterback.
The exchange of the football is supposed to be a simple action, but occasionally it gets bungled, resulting in a fumble. A fumble can be caused by the center not snapping the ball directly into the quarterback's hands (perhaps because he's worried about being hit) or by the quarterback withdrawing his hands before the ball arrives.
Because hands are essential to good blocking, centers sometimes worry more about getting their hands into position to block than cleanly snapping the ball to the quarterback. Coaches refer to those poor snaps as short-arming the ball. In other words, the center doesn't bring the ball all the way back to the quarterback's hands.
In addition to delivering the ball cleanly to the quarterback, a center must know the blocking responsibilities of every other offensive lineman. The offense never knows beforehand how the defense will set up. And unlike the offense, the defense may move before the ball is snapped, which allows a defense to set up in a vast array of formations.
The center is essentially a coach on the field, redirecting his offensive line teammates as necessary based on how the defense aligns itself. On nearly every play, the center points to the defenders and, using terminology that the defense can't decipher, gives his fellow linemen their blocking assignments.
Centers tend to be quick, smart, and even-keeled. The other linemen look to the center for leadership and stability. In addition to being mentally tough, a center needs to be physically tough so he can absorb hits from defensive players while he's concentrating on cleanly delivering the football to the quarterback.
Guards
Guards, who line up on either side of the center, should be some of the best blockers. In a block, an offensive lineman makes contact with a defensive player and uses his hands, arms, and shoulders to move him out of the way.
A guard is doing his job if he clears the way, creating a hole for a running back to run through. A guard also must be able to fight off his man — stopping the defender's forward momentum — and prevent him from rushing the quarterback on a pass play.
Tackles
Tackles tend to be the biggest linemen, and in the NFL they're generally the most athletic. (The following figure shows one of the NFL's best tackles, Ryan Clady of the Denver Broncos.)
Tackles should be the stars of the offensive line because their job on the ends of the line is to repel some of the game's best defensive linemen and pass-rushers. They need to have great agility and the strength necessary to seal off the outside when a running play occurs. (Sealing off the outside means preventing the defensive players from reaching the corner of the line and tackling the ball carrier.)
Sometimes a tackle must shove a defensive player outside when the play is designed to go toward the middle of the field. He has a lot of responsibility on the edge (the outside shoulder of the defensive end or linebacker aligned over him) because, if the tackle succeeds in containing the defensive players, the ball carrier has an open field in which to run.
Sometimes the tackle must block his man toward the inside, thus allowing the ball carrier to run wide and outside the edge. In some plays, a tackle blocks down on the defensive tackle while the guard pulls to block the defender aligned over the tackle, moving that defender away from the running lane.
Not all running plays are designed to go inside the tackles. Off-tackle runs are usually run to the strong side of the formation, where the tight end, who serves as another blocker, lines up. On off-tackle runs, the tackle must contain his man and push him inside toward the center of the line as the ball carrier runs wide, or outside the tackle. If the tackle can't move his man, he must prevent this defensive end or linebacker from reaching the edge of the line of scrimmage, shielding the ball carrier from the defensive pursuit.
