Redman, 34, was 2-5 with a 7.54 ERA in 10 games (nine starts) for the Rockies this season. He was on the Opening Day roster, but he went 2-3 with a 7.84 ERA before being optioned to Colorado Springs on May 11. Redman was recalled earlier this month when Jeff Francis went on the disabled list, but the veteran continued to struggle. In three starts, Redman went 0-2. That stretch included his last outing, when he gave up five runs in 3 1/3 innings against the Mets.
"Mark gave us everything he had," Colorado manager Clint Hurdle said. "He had two shots up here, and it didn't work the way we hoped it to."
Morillo, 24, posted a 4.58 ERA with no decisions in 36 relief appearances for the Triple-A Sky Sox this season. The right-hander, who has allowed only three earned runs and 11 hits in his last 17 2/3 innings since June 1, logged a 0.84 ERA in June.
This will mark Morillo's third Major League stint since 2006, but it likely will be a short one. Kip Wells, who has been on the disabled list since April 29 with a blood clot in his pitching hand, is expected to be activated on Monday.
Hurdle couldn't promise Redman he'd be re-signed if he cleared waivers.
"We've got to find ways to get better," Hurdle said. "Sometimes you've got to pare some personnel, take looks at different things to get better, and that's what we're in the process of doing right now."
Jeff Birnbaum is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.