DENVER -- Jairo Díaz was designated for assignment on Thursday after his continued struggles in Spring Training. The move made room for right-hander Jhoulys Chacín, who was signed in time for Thursday afternoon's season opener against the Dodgers.

Díaz, who turns 30 on May 27, moved into the closer's role early last season and earned four saves, but delivery issues escalated and led to a 7.65 ERA in 24 outings. The Rockies signed him to a one-year, $1.1 million contract to avoid arbitration and worked with him to regain the form he has shown at various points. However, a 10.25 ERA this Spring Training in nine outings, with four home runs in 9 2/3 innings, led the Rockies to upgrade.

"It was a hard decision," said manager Bud Black. "He didn't have a great spring and somebody had to be the odd man out. We'll see what happens with the waiver wire with Jairo in the next 48 hours, whether he'll be claimed or whether he'll remain in our system."

Chacín, 33, returns to the Rockies, where he went 38-48 with a 3.78 ERA in 124 games (109 starts) from 2009-14 to begin his career. He is 78-87 with a 4.04 ERA over 12 seasons with the Rockies, Braves, Brewers, D-backs, Padres, Angels and Red Sox. He spent Spring Training with the Yankees on a Minor League contract and posted a 3.86 ERA in five outings, one start.

"We felt as though we needed some length in our bullpen in the early portion of the season," Black said. "You'll see [fifth starter] Chi Chi González out there this weekend. Bringing in [Chacín] gives us another reliable long man who would give us two or three innings of length, and also potential starter depth moving forward."

"The most innings I pitched in Spring Training was three, but out of the bullpen, if you throw three or four innings, that's what they need," Chacín said.

Here is the Rockies' 26-man Opening Day roster:

Catchers (2): Elias Díaz, Dom Nuñez

First base (2): C.J. Cron, Josh Fuentes

Second base (1): Chris Owings

Third base (1): Ryan McMahon

Shortstop (1): Trevor Story

Outfield (5): Raimel Tapia, Garrett Hampson, Charlie Blackmon, Sam Hilliard, Yonathan Daza

Starting pitchers (5): Germán Márquez, Antonio Senzatela, Jon Gray, Austin Gomber, Chi Chi González

Bullpen (9): Daniel Bard (closer), Mychal Givens, Tyler Kinley, Yency Almonte, Carlos Estévez, Jhoulys Chacín, Jordan Sheffield, Robert Stephenson, Ben Bowden