Using a slot enables you to create an elusive vertical offense, lining up your team inside a boundary cornerback and replacing the full back position. You will stretch the defense vertically off of pure speed.
Line up inside of a boundary cornerback
Traditionally, slot cornerbacks have been a sub-package player. They often come into play on obvious passing situations, and are also used as a decoy for future plays. However, slot corners face a different set of challenges than their outside counterparts, and the contracts of many of these players have not caught up with the contracts of their outside counterparts.
When covering the slot, a cornerback must shadow an NFL receiver, and must operate out of a backpedal. The goal is to force the receiver to the sideline, which gives the receiver less room to run route. This is why it is crucial for a corner to be physical, and to exert influence over the receiver.
The slot receiver is also a very hot target for quick passes. The cornerback must have good hands to get open, and he must have quickness. Having good hands, quickness, and a good hand-eye coordination are all important to having success in slot coverage.