BOSTON -- Not content to take a day off after the splashy acquisition of Daisuke Matsuzaka, Red Sox general manager Theo Epstein filled out some complementary roles in the bullpen on Friday, adding two veteran setup men with postseason experience.

The first addition came via a trade, as Epstein dealt left-handed prospect Phil Seibel to the Angels for right-hander Brendan Donnelly. A couple of hours later, Boston announced the signing of free-agent lefty J.C. Romero.

The bullpen is basically the only area of the 2007 Red Sox that remains a work in progress, but both Donnelly and Romero make the team thicker in that regard. The big void that still remains is the closer's role.

"It's really too early to start assigning exact roles, other than to say that the guys who pitch the best are definitely going to have the most important roles," Epstein said. "Certainly we're going to find a closer, whether it's internal or external, before we break [camp]. As far as Donnelly and Romero go, we think both guys have a lot of talent, both guys were available at relatively low acquisition costs and both guys go a long way toward building a lot of quality depth in our bullpen."

Donnelly and Romero join a setup crew that includes veterans Mike Timlin and Julian Tavarez, and young guns Manny Delcarmen and Craig Hansen. Left-handed reliever Hideki Okajima was also signed as a free agent earlier this month. Swingman Kyle Snyder will also be in the mix for a job, along with Bryan Corey.

Until Friday, the 35-year-old Donnelly had spent his entire career with the Angels, breaking in with the World Series championship team in 2002. Donnelly was a big cog in Angels manager Mike Scioscia's loaded bullpen that year, posing a 2.16 ERA in 46 games.

Last year, Donnelly went 6-0 with a 3.94 ERA over 62 games. In his career, Donnelly is 23-8 with a 2.87 ERA. In 295 innings, he has the exact same amount of strikeouts.

"I think Donnelly can be very interesting piece of the puzzle in our bullpen," Epstein said. "He's someone who prefers to pitch in important situations, prefers to pitch later in the game. He always wants the ball. He's got a very tough, competitive makeup, which we think will be a very good fit for our situation."

With a loaded bullpen that includes Francisco Rodriguez, Scot Shields and new acquisition Justin Speier, the Angels felt they could part with Donnelly in hopes that Seibel will develop into a talent at the Major League level.

Romero was a teammate of Donnelly's in Anaheim last year and became a free agent after the Angels decided not to pick up his option for 2007. He had a down year, going 1-2 with a 6.70 ERA in 65 appearances. However, he held left-handed batters to a .211 average, permitting just 13 of 44 inherited runners to score.

"Romero is a talented guy who had a very difficult year," said Epstein. "He had trouble getting in a rhythm all year long, repeating his delivery. Certainly that's why he's available at this cost. We see him as a 'buy low' guy. [He is] somebody who is a couple of adjustments away from being a very valuable addition to our bullpen. We think he really makes sense at this cost."

During the July trade deadline in 2005, Epstein tried to pry Romero away from the Twins, but felt the asking price (Bill Mueller or Kevin Youkilis) was too high.

Seibel had been with the Red Sox organization since being claimed off waivers by the Mets in November 2003. He pitched in two games for the Red Sox in 2004 and got a World Series ring.

Seibel was then sidetracked by Tommy John elbow reconstruction surgery in 2005, but he bounced back last year to go 6-3 with a 1.24 ERA in 22 games -- 13 of which were starts -- for three different Boston farm clubs.

"We really like Seibel as a pitcher and a person," Epstein said. "He kind of had unusually close relationships with a lot of people in the front office and the player development staff. Just a great kid. He got a World Series ring with us back in 2004 [and] suffered the elbow injury. He was the best we've ever seen at rehabbing from his Tommy John [surgery]. [He has] an incredible work ethic."

Though the Red Sox might seem exceedingly deep in middle relief at this point, Epstein knows how quickly that can change.

"With the rate of attrition with pitching in general, especially with bullpens, especially with our bullpen, I think the more quality you have, the better off you'll be," Epstein said. "We're certainly looking for another piece in the closer's role. We do like a lot of these options we have. A lot of these guys have proven track records. Hopefully, with a bit of a surplus, we can choose the best guys to break camp with us, get them in the right roles and have a successful year in the bullpen. If we maintain a surplus during the season, certainly we'd entertain the notion of a trade."