The option will be worth a little over $13.9 million, which is based on Cooper's draft position of No. 4 overall in 2015.
Even though Cooper is coming off a somewhat underwhelming 2017 season, triggering his fifth-year option was a no-brainer for Oakland.
A Pro Bowler in each of his first two years, Cooper caught 48 passes for 680 yards and seven touchdowns last campaign. Football Outsiders ranked him 65th in DYAR (defense-adjusted yards above replacement) among 86 qualified wideouts.
Raiders quarterback Derek Carr came to his teammate's defense in the offseason, telling reporters Cooper wasn't healthy for much of 2017:
Keeping Cooper with the team through 2019 gives Oakland a little more time to determine whether the 23-year-old can be the No. 1 receiver for the long term. The Raiders signed Jordy Nelson in March after releasing Michael Crabtree to give Carr some more support, but Nelson, who turns 33 in May, is more of a stopgap than a cornerstone of the passing game.
Assuming injuries were a big factor in Cooper's regression in 2017, he should rebound in 2018. If that's the case, then having his salary locked in for 2019 will be a nice bonus for the team when it weighs the possibility of a multiyear extension for Cooper down the line.