Ramirez has been traded to the Los Angeles Dodgers.
The Red Sox will pay the remaining $7 million of Ramirez's contract owed for this season, ESPN.com's Peter Gammons reported.
"When a player like Manny becomes available, I don't think there's a manager in baseball who wouldn't say they're interested," said Dodgers manager Joe Torre, whose Yankees teams went toe-to-toe with Ramirez for years. "It was something that happened very quickly, obviously."
Third baseman Andy LaRoche and right-handed pitcher Bryan Morris will go to the Pirates from the Dodgers. Outfielder Brandon Moss and right-handed pitcher Craig Hansen will leave the Red Sox organization for Pittsburgh.
Wednesday's remarks by Ramirez, who has been involved in trade rumors the past few years, might have been the final straw for the Red Sox.
"The Red Sox don't deserve a player like me," Ramirez told ESPNdeportes.com. "During my years here, I've seen how they [the Red Sox] have mistreated other great players when they didn't want them to try to turn the fans against them.
"The Red Sox did the same with guys like Nomar Garciaparra and Pedro Martinez, and now they do the same with me. Their goal is to paint me as the bad guy. I love Boston fans, but the Red Sox don't deserve me. I'm not talking about money. Mental peace has no price, and I don't have peace here."
Dodgers infielder Garciaparra, who played for the Red Sox from 1996-2004, said he's always had the utmost respect for Ramirez.
"It's nice to see we've done something like this, to make a push for the next two months," Garciaparra said. "I think he'll be just fine. Manny is really a simple person. He works extremely hard. He just wants to play baseball and go home and be with his family. How can you not respect and love a guy like that?"
Ramirez, the MVP of the 2004 World Series, remains one of baseball's best hitters and has enjoyed plenty of big moments in October. But his relationship with the Red Sox soured -- again -- in recent months, prompting the All-Star outfielder to agree to the deal.
The Dodgers began the day one game behind first-place Arizona in the NL West, and were seeking a big bat. Boston, in the middle of the AL East race and chasing a second straight World Series title, wanted a productive hitter in return and got that in Bay.
At 29, Bay is a two-time All-Star and was hitting .282 with 22 home runs and 64 RBIs. Tampa Bay pursued Bay before he wound up with the Red Sox, who trail the first-place Rays by three games in the AL East.
Even before landing the enigmatic Ramirez, Los Angeles had a crowded outfield. Torre has been juggling Matt Kemp, Andre Ethier, Andruw Jones and Juan Pierre.
"You wish you had the DH," Torre said. "We didn't plan in advance how to move things around."
Ramirez had a .312 batting average with
274 homers and
868 RBIs with the Red Sox, who have won as many postseason series with their former slugger in seven and a half seasons as the Dodgers have in the past 88 years.
Ramirez drove out of Fenway Park in a silver Mercedes at about 10:50 p.m. on Thursday night, with a handful of fans watching and a couple of television cameras rolling. He didn't stop to comment.
Ramirez, 36, was hitting .299 with a team-leading 20 homers and 68 RBIs for Boston. He hit his 500th career home run this year and is one of just eight players to hit at least 20 homers in 14 consecutive seasons. Dodgers GM Ned Colletti said Ramirez will be in Los Angeles' lineup Friday night against the Diamondbacks.
Ramirez was in the final guaranteed year of an eight-year, $160 million contract, and the Red Sox held $20 million options for the next two seasons. As part of the trade, the club options were eliminated.
So when all was said and done, the Dodgers picked up a summer rental they hope will give them a shot at improving upon a woeful postseason track record in the past 20 years. Since winning the 1988 World Series, they've made just four playoff appearances and won only one postseason game.
"We figured we had to do it," Colletti said. "There was obviously a point in time that you have to make a major decision. We did and we were glad we did it. Hopefully it pays dividends. We're confident we've got one of the best hitters in baseball coming in here -- one of the best hitters of his generation from the right side.
"He's a champion, he's a winner, and we really couldn't be happier with trying to make the club better at this point in time than to do this. We wanted this player at least for the next two months, and hopefully longer. So we're willing to take the chance and go with this guy."
The Pirates looked to the future with their acquisitions.
Hansen, a 24-year-old righty, was 1-3 with two saves and a 5.58 ERA in 32 games. A first-round draft choice in 2005, he became the first Boston player to reach the majors in the year was picked.
LaRoche, the younger brother of Pirates first baseman Adam LaRoche, hit .203 with two home runs and six RBIs in 27 games for the Dodgers. A power-hitting prospect at 24, he spent most of this year at Triple-A Las Vegas.
Moss, also 24, split the season between Boston and Triple-A Pawtucket. He hit .295 with five doubles and two homers in 78 at-bats. Last year, he led the International League with 59 extra-base hits.
Morris, a 21-year-old righty, was 2-4 with a 3.20 ERA for Class A Great Lakes.
ESPN.com baseball writer Jayson Stark, ESPN.com staff writer Amy K. Nelson, ESPN The Magazine's Buster Olney, ESPN senior writer Keith Law and The Associated Press contributed to this report.