Colorado Rockies relief pitcher Jairo Diaz (37) pitches against the San Francisco Giants during the 11th inning at Oracle Park.  Kelley L Cox-USA TODAY Sports

The Rockies have designated right-handed reliever Jairo Diaz for assignment, per a club announcement. His spot on the roster goes to fellow right-hander Jhoulys Chacin, whose previously reported one-year deal with the Rox has now been confirmed by the club.

Diaz, 29, was a pleasant surprise for the 2019 Rockies, tossing 57 2/3 innings of 4.53 ERA ball — good for a 113 ERA+ at Coors Field in the juiced-ball season — out of the Colorado bullpen that year. Along the way, he turned in strong strikeout (25.7%), walk (7.8%) and ground-ball (49.4%) rates, creating some optimism that he could be a piece for them moving forward.

That wasn’t the case in 2020, however, as Diaz was tagged for 17 earned runs in 20 innings of work. His average heater plummeted from 97.1 mph to 95.4 mph, and his strikeout rate fell to 16.4% while his walk rate ballooned to 13.2%. It was a brutal season all-around for Diaz, and spring training didn’t go any better; he surrendered 11 runs on 17 hits (four homers) and four walks in 9 2/3 frames. The fact that he was out of minor-league options left the Rockies with little choice but to designate him for assignment. They’ll now have a week to trade Diaz, attempt to pass him through outright waivers or release him.

More must-reads:

TODAY'S BEST
Timberwolves big named NBA Sixth Man of the Year
Three-time Pro Bowl pass-rusher requests a trade from the Bengals
Commanders suddenly cut pass-rusher after NFL reinstatement
Watch: Pirates prospect Paul Skenes' remarkable streak ends
Cowboys make unsurprising move with Micah Parsons
Blue Jays OF placed on injured list due to hip inflammation
Jayden Daniels addresses if he'd play for Commanders
Guardians top pitching prospect shut down after setback
Lions agree to record-setting extension with OT
Sharks fire head coach David Quinn after two seasons
Marvin Harrison Jr. explains controversial predraft decisions
Reigning Cy Young winner's disastrous 2024 continues
Lions extension makes Amon-Ra St. Brown the NFL's highest-paid receiver
Ravens extend former first-round pick
Bengals make decision on three-time Pro Bowl WR
Cardinals demote former top prospect following brutal start
Peyton Manning rips Jets for failing QB Zach Wilson
Heat react strongly to claims they put 'code red' on Jayson Tatum
Steelers make notable decision on QB Justin Fields
Cardinals receive two trade offers for No. 4 pick in NFL Draft