This is usually an extra safety subbed in to cover a slot receiver or tight end, though they can be used in any number of ways.
Again, there are always adjustments to the rules as defensive and offensive coordinators try outsmart one another. For example, the Nickel defense is named so because a 5th defensive back is subbed into the game. This is usually an extra safety subbed in to cover a slot receiver or tight end, though they can be used in any number of ways. The pass-heavy modern offense has turned the Nickel defense into one of today’s most common personnel packages.