Martin pitched one-third of an inning in the loss, walking two batters and retiring Ryan Church on a long fly ball to center field. Manager Clint Hurdle delivered the news to Martin after the game.
"I need somebody to come in here and throw strikes," he said. "Tommy wasn't able to. He understood that. We had a very professional conversaton."
Martin started the season on the disabled list. After coming back on April 24, the left-hander has pitched 25 2/3 innings, allowing 32 hits and 14 runs. He said he understood the decision.
"Stuff like that happens when you're inconsistent over a period of time," he said. "They did what they had to do."
Ramirez, a right-hander, will join the team. He made his Major League debut in 2006, and saw limited action early this season before injuring his right elbow. He missed 20 games while on the disabled list, then returned to the Rockies for the latter half of May.
For Martin, a 37-year-old, the decision may mean the end of his baseball career. He said that he will wait and see if other teams display an interest in him, and talk things over with his wife.
"Sometimes you're at a place in your career where you have to make a decision," he said. "Do you want to keep going, or run off into the sunset?"
If it is the end for Martin, Thursday's game was the end of an 11-year Major League career. He has pitched in 377 games with a career ERA of 4.92. He has spent the last two years in Colorado, and said he has fond memories of the organization.
"They gave me more than my fair share of opportunities," he said.
Michael Phillips is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.