Back in 2011, the NFL and NFLPA introduced the rookie wage scale back as part of a new Collective Bargaining Agreement. Not only did it create a clear outline for how rookie contracts are to be structured — thus creating a more competitive market for higher picks — it also introduced the so-called fifth-year option.
That option gave teams the ability to add another comparatively inexpensive season to the standard four-year rookie deals signed by first-round draft selections.
The option essentially works as follows: a team picks a player in the first round of the draft, and subsequently signs him to a four-year contract.