In 1 2/3 innings over three games this week, Hanrahan has walked four batters while allowing five hits and five earned runs. Of the 25 batters he's faced this season, 11 have reached base.
Despite the struggles, manager John Farrell said he's sticking with his ninth-inning man.
"Joel is going through a little bit of a spell where things aren't clicking for him, but we're still with him," Farrell said. "We've got a guy who picked him up today in Koji who did one heck of a job to shut off that threat in the ninth."
After pitching three clean innings and picking up two saves on the road to start his Red Sox tenure, Hanrahan has struggled to consistently command his fastball. He promptly walked Evan Longoria on four straight pitches to start the ninth inning Saturday before engaging in an eight-pitch at-bat with Ben Zobrist that ended with the same result.
Hanrahan, getting clocked as high as 97 mph, was all over the strike zone in both at-bats, though he could have struck out Zobrist had David Ross caught a foul tip.
"He's trying his best," Ross said. "You try to make a good impression -- especially in a market like this, you try to make a good impression.
"I thought he wasn't letting it go like he normally does. I know he was focused on down in the zone. That was something he was trying to work on from his last outing. I know he was down in the zone a little better, but they were balls.
"What he needed to do was just let it go down there. When you're scuffling, it's like me hitting. Sometimes you're tentative and your mind gets in the way. All we need is him to have a positive outing. He works hard, he's a great pitcher and he's a big part of our team."
Farrell wouldn't say specifically if Hanrahan would work out his struggles while still pitching the ninth inning, though the manager was specific that he had not yet made a change at the time of a postgame news conference.
Hanrahan acknowledged that walking batters in the ninth inning is a habit he's trying to break.
"I'm fighting some things with my mechanics and my legs, and it's just something that I got to work on," said Hanrahan, who was 36-for-40 in save chances with the Pirates last year. "I guess I'm more of a warm-weather guy. I don't know, but it's just something that we got to fight through."