BOSTON — There’s an old saying in baseball that solo homers won’t kill you.

Ok, well, how about three solo home runs? Plus an error that allowed a run to score? And a groundout RBI? Those, those are the things that really can leave a dent. And, when a team has an inexperienced interim manager, an underperforming offense and holes in its bullpen, those things can lead to yet another devastating defeat, this time a 6-5 loss in 10 innings.

The Orioles have won just one of their last 11 games.

For the second game in a row, the Orioles took a 2-0 lead. And, once again, it was gone before they had time to enjoy it.

Zach Eflin, who six days ago allowed a career-high-tying eight runs, once again struggled at the start. He gave up a leadoff home run to Jarren Duran on the second pitch of his outing, then, as rain pounded Fenway Park for the third day in a row, had to retreat into the dugout.

The Orioles and Red Sox avoided having yet another delay in a series that has seen one delay and two postponements, but a break in play so the groundskeepers could tend to the field was less than ideal. When Eflin resumed, after completing another round of warm-up pitches, Wilyer Abreu also took him deep.

“It’s not easy, but it’s part of the job,” Eflin said of the interruption. “Just kind of got to figure out a way to get through it, try to get a dry ball, try to get some dry mud out there. But it’s part of the game.”

In the bottom of the fifth, with the Orioles up 5-2 after a three-run top of the inning, Eflin gave up his third solo home run of the game, this one to Abraham Toro. All three came against his cutter and were on the first or second pitch of the at-bat.

Eflin, who allowed just 10 home runs in his first 13 starts with the Orioles after they acquired him at the trade deadline last July, has allowed seven in his last two starts.

“The cutter’s been getting hit pretty hard,” Eflin said. “I don’t know if it’s something I’m doing differently. I think just being more stubborn about being north and south and understanding when it’s my turn to throw my pitches and when I need to be in the zone and stuff and blending those two together. It’s frustrating. I’m not happy with how I’ve been pitching the past two outings.”

Eflin stayed in for the sixth, but a run scored on an error by Gunnar Henderson and, after Bryan Baker took over, another run came in on a groundout.

Alas, the game was only tied. The Orioles’ bullpen — which a day prior allowed 10 earned runs, not even including the eight that position player Emmanuel Rivera let in — held the Red Sox scorless until the ninth, keeping the game tied as the Orioles failed to take advantage of having runners on in the seventh and eighth.

After trading 1-2-3 ninth innings, the Orioles and Red Sox went to the 10th. The Orioles, once again, failed to do anything consequential, having had just one hit in their last five innings. Interim manager Tony Mansolino sent out Gregory Soto because, he said, he wasn’t comfortable having Félix Bautista go back out. Bautista threw only 10 pitches in the ninth inning but has not pitched more than one inning since returning at the beginning of the season from Tommy John reconstructive elbow surgery.

So out came Soto, who got to face the top of the Red Sox lineup. Mansolino said he wanted Soto to throw his best stuff to Rafael Devers and not to pitch around him. Instead, Soto threw a fastball right down the middle that Devers smacked for an RBI single to walk it off.

“You’ve got a really good lefty that’s done it in the big leagues for a long time against, obviously, a really good hitter, but we’re gonna bet on our guy if we can,” Mansolino said, adding later, “I don’t think he’s trying to throw it right down the middle. You can probably ask him, but my assumption is he’s trying to throw it somewhere else.”

Game 2 of the doubleheader is scheduled to begin at 6:35 p.m.

This article has been updated.