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.

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