In most sports, the best players must quickly diagnose a play and react decisively. But reaction time is especially important in football, because plays develop quickly, last only a short time and feature massive athletes racing all about the field. Regardless of your position on the team, the quicker you're able to react to any set of circumstances, the better your chances of making the play.
There's no position in football in which reaction time is more important than quarterback. In a 2011 study of standout college quarterbacks by ESPN's Sports Science, the average time it took them to react to an infrared beam of light was two-thirds of a second. Although quarterbacks may have slightly more time to pass the ball in real-game situations, they also must react to oncoming pass-rushers, locate open receivers and make sure no defensive backs are lying in wait before quickly unleashing one accurate throw after another.
There's a football saying that states that cornerbacks must be able to "play on an island." Unlike other players who play in the middle of the field, cornerbacks often find there's no one there to help them. Meanwhile they must maintain stride-for-stride coverage of speedy wide receivers, who have the advantage of knowing which direction they're headed in. A cornerback must also quickly determine whether the play is a running or passing play and react by either sprinting toward the line to make a tackle, or quickly backpedal and stay in front of the receiver.
Linemen are thought of as the big lugs of a football team, relaying more on raw strength and toughness than cat-like reflexes. But that's not necessarily the case. Linemen have the disadvantage of starting the play in a three-point stance, hunched at the waist with one hand in the dirt. From there, they must uncoil their often-mammoth bodies and explode into an athletic stance within a millisecond of the ball being snapped. A defensive lineman slow to react to the snap is usually neutralized, whereas a lumbering offensive lineman will be blamed for his man racing past him and chasing down the ball carrier.
Punt returners are often the quickest players on their teams. The reason: While the punt returner stands, eyes trained on the earthbound ball in the sky, the opposing team is racing down the field with the sole objective of knocking his head off. By the time a punt returner catches the ball, there are often several players within a few yards, sprinting toward him with 40 yards worth of momentum at their backs. The punt returner must keep his eye on the ball, catch it and then quickly dart in and out of traffic while diagnosing his best running lanes based on the location of the defenders and his blockers.