Coming over along with Bailey in the deal is outfielder Ryan Sweeney. To get Jonathan Papelbon's successor for the ninth inning, the Red Sox traded right fielder Josh Reddick and two prospects -- 20-year-old third baseman Miles Head and 19-year-old righty Raul Alcantara.
Red Sox general manager Ben Cherington had been discussing Bailey with Oakland GM Billy Beane for the last several weeks.
"Andrew is a proven top-quality closer in the American League," Cherington said. "He's done it for three years in the American League, he's had a lot of success. 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 -- who was born in New Jersey and spends his offseasons in Connecticut -- is pleased to be going to a top contender that plays in the Northeast.
"I'm very excited. This is where my family and I live in the offseason," the 27-year-old Bailey said. "You can't get much further than Oakland to the East Coast. I'm definitely excited to play baseball on the East Coast and for the Red Sox."
And Bailey already has a solid relationship with his new manager Bobby Valentine. They've collaborated on charity work in Connecticut in recent years.
"I spoke to Bobby after I got off the phone with Ben Cherington. Bobby and I are good friends," Bailey said. "He does a lot with the foundation I'm a part of. Bobby and I have a good relationship and he's excited to have me on board and I'm excited to be there for him. We're both looking forward to it and it just kind of helps knowing someone going in."
The right-hander pitched in 42 games last season, notching 24 saves. He missed the first two months of the season with a right forearm strain. Bailey also missed a month in 2010 with a strained intercostal muscle.
However, the Red Sox did extensive background checks on Bailey's health before consummating the trade, and they are confident he will hold up.
"We had a chance to look into Bailey's medical history and get to know a lot more of what he went through," Cherington said. "He had Tommy John surgery about five years ago and he's fully recovered from that. He had some elbow symptoms in 2010 and had a relatively minor procedure after the 2010 season. He then came to Spring Training in 2011 and perhaps ramped up too quickly and had a little bit of a setback and appeared to be some scar tissue breakup and some minor soft tissue injury.
"He was able to recover from that, get back to pitching and perform well. His stuff and his performance were solid down the stretch and he was systematic for the rest of the season after he came back. We are very confident he'll come into camp ready to go and ready to help our team in 2012."
Bailey has never felt better about his health entering a season.
"I'm feeling good, to be honest with you," Bailey said. "This is my first healthy offseason I've had since I've been in the big leagues. In 2009, I had a little procedure done on my knee that I had to rehab in the middle of December. Last year was the bone chips and bone spurs being taken out and that kind of lingered into Spring Training and into the season. That being said, this is the first time I've been healthy and not having to rehab anything until the middle of December or even into Spring Training. I've been able to get after it from Day One and so far, knock on wood, healthy and strong and looking forward to Spring Training."
Bailey has pitched 157 games in the Majors, finishing 133 of them. He has a 2.07 ERA.
Boston's bullpen is starting to come together. In Bailey, the recently acquired Mark Melancon and Bobby Jenks, the Red Sox have three pitchers with closing experience.
Daniel Bard will go to Spring Training as a starter and will likely be able to remain there now that Bailey has been added to pitch the ninth inning.
The inclusion of Reddick in the deal creates a question mark in right field for Boston.
Ryan Kalish, who impressed the Red Sox over the final two months of the 2010 season, is an option. But Kalish injured his shoulder in a collision last April and missed most of the season. He had neck surgery during the offseason.
The newly acquired Sweeney, 26 and a left-handed hitter, will be in the mix. He hit .265 with a homer and 25 RBIs in 264 at-bats for Oakland in 2011.
"Ryan Sweeney we expect to be a big part of our outfield mix," Cherington said. "He can play right field. He's a good defender. His versatility is kind of like Reddick, really, both of them can play both outfield spots and play them well.
"Sweeney has played in a big ballpark in Oakland and handled the defensive part of the game well. We also really like his offensive approach to Fenway. He's got an opposite-field approach. He's a guy we tried to acquire in the past and think he fits well with our team. So he'll be a big part of our outfield mix."
The Red Sox also have Darnell McDonald and Mike Aviles on their roster. Aviles has been mostly an infielder during his career but has spent time in Puerto Rico this winter working on his comfort level in the outfield.
"We still have Darnell McDonald on our roster, who has done a good job for us in the past and has hit left-handed pitching," Cherington said. "We got good reports on [Aviles] when he was in Puerto Rico. Obviously we like him as a hitter and as an offensive player. We think we have some internal solutions for right field and Sweeney is a big part of that."
The 24-year-old Reddick should settle nicely into Oakland's outfield mix. He got off to a red-hot start for Boston last year before cooling off down the stretch.
Bailey, the American League Rookie of the Year in 2009, is looking forward to tasting a pennant race for the first time.
"It's something that I think every kid out there playing tee-ball strives to pitch in the postseason and in meaningful games in September and ultimately the World Series," Bailey said. "I'm going to welcome that with open arms. It's not going to change the style that I attack the hitters. I'm aggressive and like to go right after guys. As long as I stick to my guns and trust my stuff, I'll be fine, I'm sure."
Though Bailey doesn't have an overpowering fastball, he has a fearless approach.
"I'm not going to blow by you at 98-99 [mph]," he said. "I'm not that kind of guy. I sit in the low 90s, rely on control and getting ahead of guys. The motto I live by is 'strike one is the best pitch in baseball.' As long as you stick with that, you'll be fine.
"Obviously, pitching, and closing for that matter, is bigger in Boston. Obviously the market's a lot bigger, but I think I'll be fine with that. The last three years have been great, being able to close against the teams I'm going to be closing against in the same league. It's not like I'm going to different territory or a new league that I need to know all the hitters.
"It's the same guys I've been facing for the last three years, just with a different uniform on. The only things I can work on are one, obviously staying healthy and two, sticking to my guns and being who I am. Just because I'm wearing a different uniform doesn't mean I'm going to change on or off the field."