Football players with size and strength often have a tremendous advantage over other players, but smaller players can make up for their lack of size with quickness, speed and power. Players who lack height do not necessarily lack strength. Shorter running backs, linebackers and wide receivers still can be impact players.
Hiding From the Defense
A running back who lacks height can be difficult for the defense to find. When the running back lines up behind the fullback, it can be hard for the defense to see him. If the quarterback gives him a quick pitchout and the running back can get to the outside quickly and get one well-placed block, he can be deep in the secondary before some of the defensive personnel know who has the ball.
A running back who lacks height might not lack power. Many coaches and general managers like running backs who are shorter and more powerful for interior running plays, especially on third-and-1, fourth-and-1 and goal line situations. Running backs who are shorter can initiate contact with taller tacklers by driving a shoulder into the opponent's midsection and driving him backward.
Most head coaches want taller receivers who can go over the top of the defense to make big catches, but bigger wide receivers are vulnerable to the big hit from the defensive back when they have to extend themselves to catch the ball and it takes them an instant longer to elude the hit. A shorter wide receiver can contort his body a fraction of a second quicker after making the catch, and that advantage might allow him to avoid the big hit.
A shorter linebacker can be an outstanding run defender and might have an advantage over a taller linebacker in that area. Linebackers often have to take on offensive linemen before making the tackle. A shorter linebacker can get underneath the blocker and neutralize the offensive lineman's size and strength. He can then play off the block and make the tackle. Shorter linebackers use their quickness and aggressiveness to shut down the running game.
Center of Gravity
A shorter player also has an advantage over a taller player because he has a lower center of gravity. The lower you hit your opponent, the more force you have. You will be able to drive your opponent backward when you hit him lower than he hits you. Coaches at all levels constantly preach that "low man wins" in all individual blocking and tackling drills, and that applies to running backs who are blocking.