Short motion is exactly as its name describes. On short motion, the receiver runs inside towards the offensive linemen. The offense always snaps the ball before the motion player gets to the offensive tackle or tight end. This allows them to build momentum, gain leverage, and get into any in-breaking route much quicker. Teams will also use short motion to bring their receiver in to help on crack blocks or on sealing the end man on the line of scrimmage for an outside run.
Short motion doesn’t just have to be used to gain momentum and leverage inside, though. If defenders follow or bump with the motion, offenses can then use the defense’s adjustment against them and quickly attack the vacated space outside. Short motion can be a designed part of the play or used as a way for the quarterback to help create a better look while at the line of scrimmage.