The White Sox have traded outfielder Carlos Quentin to the Padres for two prospects. San Diego general manager Josh Byrnes is bringing Quentin back four years after trading him to Chicago as an executive with Arizona. "It's exciting. First of all with the trade happening this morning, your whole life has been shifted," Quentin said. "It will take time to set in but it's exciting that it's shifting to San Diego where I grew up. It's definitely a positive to me and I look forward to contributing to the Padres." The White Sox received minor league pitchers Simon Castro, a right-hander, and Pedro Hernandez, a left-hander.

The Red Sox have acquired reliever Andrew Bailey from the Athletics in exchange for outfielder Josh Reddick, according to sources. Bailey compiled 24 saves last year in Oakland to go along with a 3.24 ERA -- the highest earned run average in the right-hander's three years in the majors. He is expected to replace Jonathan Papelbon, who left as a free agent, as Boston's closer. The Red Sox will also receive outfielder Ryan Sweeney in the deal.

The Cubs and Reds have agreed in principle to a trade that will send pitcher Travis Wood and two minor-leaguers to the Cubs for left-handed reliever Sean Marshall, according to a source familiar with the situation. Marshall, 29, could be used as a set-up man or as a possible closer, due to the fact Cincinnati's closer Francisco Cordero is a free agent. He is set to make $3 million in 2012, and he will be a free agent after the season.

The Rangers have acquired catcher Luis Martinez from the Padres for minor league pitcher Ryan Kelly. Martinez batted .203 (12 for 59) in 22 games for San Diego with one homer and 10 RBIs. He homered for his first big league hit on July 27 against Arizona.

The Red Sox have acquired reliever Mark Melancon from the Astros in exchange for infielder Jed Lowrie and right-hander Kyle Weiland. Melancon, 26, took the reins as Houston's closer in May and recorded 20 saves in 25 chances. He was 8-4 on the season with a 2.78 ERA and 66 strikeouts in 74 2/3 innings. He made only $421,000 this year and likely won't be eligible for salary arbitration until after the 2013 season. "We like his stuff, toughness and experience in the ninth inning," Red Sox general manager Ben Cherington said. "His command and cutter both improved as the year went on."

The Red Sox have traded infielder Jed Lowrie and pitcher Kyle Weiland to the Astros for relief pitcher Mark Melancon, a baseball source confirmed to ESPN.com's Jerry Crasnick. The Red Sox might have found the successor to Jonathan Papelbon in Melancon.

The Pirates have acquired third baseman Casey McGehee from the Brewers in a trade for reliever Jose Veras. The deal came just hours after the Brewers agreed to terms with free-agent third baseman Aramis Ramirez. McGehee had a strong rookie season in 2009 and a big year in 2010, but slumped at the plate in 2011 and lost his starting job to Jerry Hairston Jr. late in the season.

The Phillies have traded outfielder Ben Francisco to the Blue Jays for minor league left-hander Frank Gailey. Francisco spent parts of three seasons with Philadelphia, hitting .259 with 17 home runs and 75 RBIs in 225 games. Gailey, a 26-year-old native of Philadelphia, split last season between Single-A Dunedin and Double-A New Hampshire. He was 5-6 with a 3.41 ERA in 45 relief appearances.

The Nationals acquired Ryan Perry from the Tigers for Collin Balester on Friday in a swap of right-handed relievers who split 2011 between the majors and minors. Perry went 5-6 with two saves and a 4.07 ERA in 161 1-3 innings across 149 relief appearances over three seasons with Detroit. Balester was 5-16 with a 5.17 ERA in 62 games -- 40 in relief -- from 2008-11 in Washington.

The D-Backs added a front-line starter Friday and boosted their bullpen, acquiring pitchers Trevor Cahill, Craig Breslow and cash from the A's. The A's received starting pitcher Jarrod Parker, outfielder Collin Cowgill and reliever Ryan Cook in the trade Friday, all players the A's envision could be on the major league roster in 2012.