The Boston Red Sox took a major step toward revamping their pitching staff, acquiring closer Andrew Bailey in a five-player trade with the Oakland A's on Wednesday.

The Red Sox will also receive outfielder Ryan Sweeney while sending outfielder Josh Reddick and minor leaguers Miles Head, a corner infielder, and Raul Alcantara, a right-handed pitcher, to Oakland.

Bailey, 27, was the AL Rookie of the Year in 2009 and had 24 saves, a 3.24 ERA and 41 strikeouts in 41 2/3 innings for Oakland last season. In three big league seasons he's posted a 2.07 ERA, 0.95 WHIP and 75 saves.

The Red Sox lost long-time closer Jonathan Papelbon earlier this offseason when he signed as a free agent with the Philadelphia Phillies for four years and $50 million.

Bailey's addition likely means Daniel Bard (3.33 ERA in 73 innings in 2011) will shift from setup man to Boston's starting rotation. Earlier this month the Red Sox traded for right-hander Mark Melancon from the Houston Astros. Melancon, 26, had 20 saves last season but will likely slide into Bard's setup role.

"I love the Bay Area, but if you're going to get traded, I can't think of a better situation for myself and my family to be in," Bailey told mlb.com. "It's a big market, big team, and I'm excited about the opportunity to win over there, especially knowing Bobby (manager Valentine)."

Red Sox general manager Ben Cherington told RedSox.com the team likes Bailey's track record and character.

"He's done it for three years in the American League," Cherington said. He''s converted a high percentage of his opportunities. He's got the stuff. We really like his makeup for Boston and everything we've learned about him the last few weeks has only strengthened our conviction that he can fit in really well to our team and our clubhouse."

Bailey did miss the first two months of last season with a strained forearm.

In Sweeney, the Red Sox get a versatile player who could become their fourth outfielder. He played all three outfield spots last season and generally displays good plate discipline (.342 career on-base percentage) although lacking power (.378 slugging).

Reddick, 24, had surgery on his left (non-throwing) wrist in November. He will have a shot to crack the Oakland outfield. He batted .280 with seven homers and 28 RBI in 87 games for the Red Sox last season.

A larger question for the A's: Who will pitch? They've now traded three former All-Stars in Gio Gonzalez, Trevor Cahill and Bailey.

The A's, eyeing a possible move to San Jose, have also parted with outfielders Josh Willingham and David DeJesus as they stockpile prospects this offseason. Coco Crisp also appears unlikely to return, providing Reddick an excellent opportunity to gain regular playing time.

Head and Alcantara are long-range prospects. Head, 20, batted .299 with 22 homers and 82 RBI in Class A last season. Alcantara, 19, is 6-7 with a 2.72 ERA in his first 26 professional starts in rookie league and Class A.

Of the first 500 who responded to a Boston Globe survey on line, 91% said the Red Sox improved their team with the trade.

Also on Wednesday, the New York Yankees signed former Red Sox reliever Hideki Okajima to a minor-league deal. The left-handed Okajima, 17-8, 3.11 in 261 games for Boston, spent most of last season at Class AAA Pawtucket, going 3-1 with a 2.29 ERA.