Chacon, who went 1-7 with a 4.09 ERA for Colorado in 13 games (12 starts) will likely join the Yankees in the Bronx on Friday and take the ball against the Angels on Saturday at Yankee Stadium.
The Yankees sent right-handers Ramon Ramirez and Eduardo Sierra to the Rockies for Chacon, a 27-year old with a 24-45 career record and 5.20 ERA in parts of five seasons with the Rockies.
"We've been looking for pitching, and I've talked with Colorado in the past," said general manager Brian Cashman. "He'll slot into our rotation here and hopefully help us."
Chacon's most productive season came in 2004, when he served as the Rockies' closer. He saved 35 games for Colorado that season, but he did blow nine opportunities, going 1-9.
In 2003, Chacon had his best year as a starter, going 11-8 with a 4.60 ERA in 23 starts. That summer, he represented the Rockies in the All-Star Game in Chicago.
"At this point, I don't know what they have in mind," Chacon said of his role with the Yankees. "All I know is I'll start Saturday, so I'll be in the starting rotation for now. Until that situation arises, I won't think about that."
With Carl Pavano, Jaret Wright, Chien-Ming Wang and Kevin Brown currently on the disabled list, the Yankees will use Chacon as a starter until they get a little healthier. Randy Johnson, Mike Mussina and Al Leiter are currently in the rotation, while Aaron Small has won both of his starts.
"In Shawn's case, we're not acquiring a savior," Cashman said. "We're just getting a guy who we think can help us win games and stabilize the back of the rotation."
The Yankees first contacted the Rockies about the possibility of acquiring Chacon during the All-Star break, but Colorado asked for left-hander Sean Henn and right-hander Scott Proctor, which the Yanks considered to be too high a price. New York countered with Ramirez and Sierra, but Colorado wasn't interested.
Thursday, the Rockies lowered their asking price and accepted the two Double-A hurlers in exchange for Chacon, who is making $2.35 million this year and is owed $847,000 over the final two months of the season. Chacon has two more years of arbitration eligibility before he becomes a free agent.
Cashman wouldn't project how or if Chacon figures into the team's plans beyond 2005, saying that his focus is on the rest of this year's campaign.
"We're going to see what we see," Cashman said. "My whole purpose has been to acquire talent without disrupting the major pieces of our system. No one is promised tomorrow; we're just living game-by-game."
Ramirez, 23, was signed by the Yankees as a non-drafted free agent in March 2003. He went 6-5 with a 3.84 ERA in 15 starts for Trenton, striking out 82 batters in 89 innings. In six starts for Triple-A Columbus to open the season, Ramirez was 1-3 with a 5.33 ERA.
Sierra, a 23-year-old acquired by the Yankees in December 2003 from the A's in a deal for Chris Hammond, went 3-1 with two saves and a 3.28 ERA in 33 relief appearances for Trenton this season.
Despite his poor win-loss record, Chacon feels that he did the job that was asked of him in Colorado, where the Rockies' 36-64 record entering Thursday was easily the worst in the NL. He has given up three or fewer runs in nine of his 12 starts, but is winless in his last 10 starts.
"It was frustrating, losing," Chacon said. "Obviously the record, 1-7, is not good at all. But when I sit back and think about it, I know that I did my job, that was to keep us in ballgames, go out, pitch six, seven innings, keep us close and give us a chance to win."
Chacon now finds himself in a pennant race after spending the entire season languishing in last place in the National League West. The Yankees are 1 1/2 games behind the Red Sox in the American League East. New York also trails Oakland by just a half-game for the Wild Card spot, though the teams are tied in the loss column.
"That's exciting for me. It's an opportunity for me to go out and grab it," Chacon said. "I don't think I'm going to get a better opportunity now, at this point in my career, to have a chance to win, be in the playoffs, hopefully be in the World Series. This is a big, big opportunity for me to do something special in my career."
Mark Feinsand is a reporter for MLB.com. Thomas Harding contributed to this report. This story was not subject to the approval of Major League Baseball or its clubs.