"[Andrews] basically walked in, looked at my arm, touched it, and said there really wasn't a decision," Hanrahan said. "The flexor pretty much tore right off the bone. It wasn't really a decision. It's just a matter of what kind of surgery it was going to be. As of now, it's just going to be the flexor. When he gets in there and takes a look, it could be worse, [or] it could be not as bad."
After saving 36 games in 40 chances and posting a 2.72 ERA for the Pirates last season, Hanrahan was 4-for-6 in save opportunities for the Red Sox while walking six batters in 7 1/3 innings and accumulating a 9.82 ERA.
"This is a guy that's 31 years old," said manager John Farrell. "And yes, free agency is pending, but you have to do what's right for the guy.
"You don't want a short-term solution or a quick fix. This is something that's got to be taken care of hopefully once, and then he has a long and productive career following."
Hanrahan was acquired from the Pirates in December, along with infielder Brock Holt, for Stolmy Pimentel, Ivan De Jesus, Mark Melancon and Jerry Sands. Hanrahan agreed to one-year deal worth about $7 million, so he'll be looking for employment following this season. He said the Red Sox haven't yet discussed future contract negotiations with him.
"Hopefully I'll get another chance here, maybe, and show the fans here what kind of pitcher I really am," Hanrahan said. "This year has kind of been a wash. Now it's definitely a wash. We'll see where it takes me from there."
Hanrahan said he wasn't sure if the damage in his arm was built up over time or if it happened in one sudden motion. But with the frequency in which pitchers bounce back from arm surgeries thanks to modern science, the right-hander is feeling optimistic.
"With the guys that are doing it these days and the programs they have, surgery is kind of like putting a Band-Aid on something," Hanrahan said. "They're so good at their job, kind of like we are. It takes a lot of the worry out of everything."
The Red Sox are using Junichi Tazawa as their closer for the time being, while Andrew Bailey recovers from a right biceps strain. Farrell said Bailey will likely start throwing from the mound at some point next week, and a rehab assignment may not be needed before Bailey returns.
Bailey is eligible to come off the 15-day disabled list on Tuesday.