By Jeff Louderback

Earlier in December, the Boston Red Sox bolstered their bullpen by signing veteran right-hander Koji Uehara to a one-year deal. On Saturday, the club acquired right-handed closer Joel Hanrahan from the Pittsburgh Pirates for outfielder/first baseman Jerry Sands and right-handed pitcher Stolmy Pimentel.

The 31-year-old Hanrahan, who is projected to receive $6.9 million through arbitration in 2013 and can become a free agent next offseason, was 5-2 with a 2.72 ERA and a 1.27 WHIP while earning 36 saves for the Pirates in 2012. He struck out 67 in 59.2 innings, allowing just 40 hits, but his 5.4 walks per nine innings ratio is a concern. In 2011, Hanrahan walked only 2.1 batters per nine innings while logging a 1.83 ERA, a 1.05 WHIP and 40 saves.

Projections range on Sands. SoxProspects.com says that he “projects as a bench player at the Major League level, capable of filling in during stretches.” CBSSPorts.com’s Jon Heyman Tweeted that Sands is “a terrific athlete with power.” Heyman added that Sands has a high ceiling and compared him to a Matt Holliday type.

Likely, the SoxProspects.com description is more accurate. When they acquired him from the Los Angeles Dodgers in last summer’s blockbuster deal, the Red Sox envisioned Sands as a first baseman and left fielder off the bench in 2013.

Once a highly regarded prospect, the 22-year-old Pimentel has struggled the last two seasons. He logged a 9.12 ERA in 15 starts at Double-A Portland to open the 2011 campaign and was demoted to advanced Single-A Salem, where he had a 4.53 ERA in 11 games (10 starts) while attempting to regain his confidence. In 2012, Pimentel was 6-7 with a 4.59 ERA in 22 starts at Portland.

The move clears space on Boston’s crowded 40-man roster. If the signing of Mike Napoli is finalized, the Red Sox will likely acquire a left-handed hitting first baseman/corner outfielder (like Seattle’s Mike Carp). Sands was expendable since he is a right-handed bat. Boston also has right-handed slugging first baseman Mauro Gomez on the 40-man roster.

The addition of Hanrahan would further bolster what is shaping up to be a strong Red Sox bullpen. Hanrahan will likely compete with Bailey for the closer’s role. Though the 28-year-old Bailey struggled to a 7.04 ERA in 19 games after returning from thumb surgery that he underwent at the end of spring training, he is a proven closer when healthy, as his three seasons in Oakland indicate.

Uehara has closing experience, though he is best suited as a set-up man at this stage of his career. Junichi Tazawa, who delivered an impressive performance in 2012, will serve as a a key late-inning reliever. Franklin Morales and Alfredo Aceves give the Red Sox two arms capable of filling a set-up role, a long relief job and a spot starter.

The Red Sox hope that reuniting with John Farrell and returning to a full-time relief role will resurrect Daniel Bard, who suffered through an atrocious 2012 season. Left-handers Craig Breslow and Andrew Miller, and right-handers Mark Melancon and Clayton Mortensen, will also be competing for spots on the Opening Day roster.