The Red Sox made official their addition of lefthander Craig Breslow on Wednesday. He had agreed to a one-year, $2 million deal Dec. 19.

But general manager Ben Cherington said he is “still working” on more additions to the bullpen. Nothing is close but the Red Sox are not yet satisfied with their options behind closer Koji Uehara.

Breslow is coming off the worst season of his nine-year career. He had a 5.96 ERA in 60 appearances and allowed a startling 73 hits — eight of them home runs — in 54⅓ innings.

Lefthanded hitters batted .291 against Breslow with an .838 OPS.


The Red Sox declined Breslow’s $4 million option after the season, then investigated other options for more than two months before bringing him back for half as much.

Breslow had a plausible excuse for his demise. Counting the postseason, he made 71 appearances in 2013 and was worn out by the end of the World Series.

Breslow was unable to undertake his usual offseason workout program and could not pitch in spring training. He opened the 2014 season on the disabled list with a shoulder strain.

His performance was rocky as a result. Breslow was hit hard in April, recovered over the two months that followed, but had a 7.17 ERA after the All-Star break.

Breslow joins a bullpen largely devoid of proven lefties. The Sox have 25-year-old Drake Britton, who has 25 major league appearances, and 30-year-old Tommy Layne, who has pitched in 70 games over the last three seasons, 30 with the Red Sox last season.

Layne had a 0.95 ERA and 1.16 WHIP last season. All but one of his appearances came in the final two months of the season for a last-place team already in rebuilding mode.

The Sox designated catcher Dan Butler for assignment to make room for Breslow on the 40-man roster.


Butler, 28, made his major league debut last season, going 4 for 19 with three doubles and two RBIs in seven games. He spent most of the season with Triple A Pawtucket.

Signed as an undrafted free agent in 2009, Butler hit .256 in six minor league seasons. Butler could return to the Red Sox if he clears waivers.

Peter Abraham can be reached at pabraham@globe.com. Follow him on Twitter @peteabe.