Diaz, Castro promoted from Triple-A

Betancourt designated for assignment; Miller optioned to Albuquerque

Diaz, Castro promoted from Triple-A

DENVER -- With Colorado desperately needing relief for its often-used and ineffective bullpen, the Rockies called up two fresh faces on Sunday.

Right-handers Simon Castro and Jairo Diaz were promoted from Triple-A Albuquerque before Colorado's series finale with the Mets. Veteran reliever Rafael Betancourt was designated for assignment and Justin Miller was optioned down to Albuquerque as the corresponding moves.

Both of the callups appeared in Colorado's 5-1 loss to the Mets at Coors Field. Castro threw two innings with a strikeout and two hits surrendered, while Diaz threw one inning with a walk and a strikeout.

"I thought they did a great job," Rockies manager Walt Weiss said after the game. "Simon settled in after some issues in that first inning, but kept them from scoring. And I think Diaz showed why we like him -- the power that you envision at the back end of a bullpen and the swing-and-miss slider."

Castro's first Rockies strikeout

In one of the early noteworthy moves by first-year general manager Jeff Bridich, Diaz was acquired from the Angels last December in a trade for infielder Josh Rutledge. Weiss described Diaz as a "big-time arm" who has the ability to reach triple digits in mph.

Diaz, the Rockies' No. 27 prospect, struggled early with control this season in Triple-A -- he had 21 walks, 19 strikeouts and a 6.08 ERA through his first 25 games -- but those numbers have turned around of late. Over his final 22 games, Diaz produced a 3.18 ERA and a 1.9 strikeout-to-walk ratio.

"We've been anxious to get a look at him," Weiss said. "It'll be good to see him in some Major League games."

Castro, meanwhile, was signed as a free agent in April 2014. He appeared in four games with the White Sox in 2013, going 0-1 with a 2.70 ERA in 6 2/3 innings before needing Tommy John surgery in January 2014.

In 36 games with Albuquerque this season, Castro was 5-5 with a 3.79 ERA.

"I feel like I have an opportunity to prove myself up here," Castro said. "I've been getting better and better every time out."

Castro, who's made 146 Minor League starts, said he could see himself as either a starter or a reliever long term, but he's happy to help the bullpen in the meantime.

Weiss said Castro could go multiple innings -- 20 of Castro's 36 appearances this season lasted more than one frame.

"He's had a good year," Weiss said. "It's a great story in itself. If you look at his road back to the big leagues, it's a great story. He's a great person, and he's persevered for the last couple years to get back here.

"He's a guy that's been a multi-inning guy down there. He's been very effective throwing the ball well -- adds more power to the bullpen with a mid-90s fastball. He's a piece we definitely need."

Worth noting
• Weiss reported no problems with catcher Nick Hundley, who took a foul ball off his mask on Saturday and later exited the game.

• After winning, 14-9, on Friday and Saturday, the Mets are just the second team in MLB history to win back-to-back games against the same team, by the same score and have more than 20 runs scored in each game. The other team was the 1927 Brooklyn Dodgers, who beat the Pirates, 11-10, on both June 11 and June 12.

Dargan Southard is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.