BOSTON -- The Red Sox emptied their bench, gave up the designated hitter and used nearly all of the arms they had available in the bullpen in an effort to salvage the finale of a frustrating three-game series against the Orioles.

But it wasn’t enough, mainly due to a pair of defensive malfunctions in the top of the eighth, when a lead slipped away for the second straight night.

The Orioles pounced on Boston’s sloppiness and swept the Red Sox with a 9-4 final score in 10 innings.

Lack of execution on defense has become habitual through the first 11 games for the Sox, who lead the Major Leagues with 15 unearned runs. Only the Athletics (15 errors) have made more than Boston’s 13.

Making it all the more frustrating is that improving the defense from last season is a top goal for manager Alex Cora and his coaching staff.

“We're not converting outs,” Cora said. “That's something we've been talking about the whole time.”

With third baseman Rafael Devers (sore left shoulder) day to day and shortstop Trevor Story (fractured left shoulder) out for the season, the Red Sox infield paid the price.

“We’ve got to turn the page with Trevor,” Cora said. “He’s not gonna be here. That's the bottom line, and we have to step up. Whoever is playing, they're capable. They showed it in camp. We played some clean baseball. And now, obviously, the lights and the third deck come into play and every game matters. Every inning matters and we just have to slow the game down and make plays.”

Boston had a 2-1 lead going into that fateful eighth.

But things soured quickly when Pablo Reyes, making the start at third in place of Devers, made an error on top prospect Jackson Holliday’s routine grounder to open the frame.

Despite the error by Reyes, the Sox were in position to escape the inning with the lead intact when Adley Rutschman hit what looked like a tailor-made double play right at second baseman Ceddanne Rafaela. But rookie shortstop David Hamilton -- recalled last weekend to replace Story on the roster -- missed the bag, and Boston only got the out at first.

“I just got to the bag and Rafaela was pretty close to it so I just assumed that he would get there himself,” Hamilton said. “But I mean that's wrong of me to assume that. I’ve gotta be there and be ready to turn the play. Not much else to say.”

As good teams tend to do, the Orioles pounced, and Anthony Santander immediately followed with a two-run homer to give the Orioles their first lead of the night.

While all errors are not created equally, Cora loathes the kind his team has been making.

“It’s been routine plays,” Cora said. “I always said, the metrics are the metrics and you want to be great at that, but the routine plays we have to turn into outs.”

At this point, Cora isn’t compelled to move Rafaela, his primary center fielder, to shortstop as a way to stabilize the infield defense. The plan for now is for Hamilton and Romy Gonzalez to form a platoon at short.

“We consider Hammy a good defender,” Cora said. “We’re going to move pieces, we’re going to move them around and maximize the lineup and the platoon. We’ve just got to keep getting him repetitions there. He's a good defender. And we’ll keep running him out there.”

Give the Red Sox credit for this: They shook off the defensive miscues quickly when Connor Wong belted a pinch-hit, solo homer to tie it up in the bottom of the eighth.

But that comeback was short-lived when reliever Isaiah Campbell (one inning, four hits, six runs, five earned) got roughed up in the top of the 10th. This came one night after Campbell gave up three runs in an inning as a 5-0 lead started to slip away and turned into a 7-5 loss.

Another consequence of giving away outs is that the bullpen is asked to do more. Under normal circumstances, Cora likely would have stayed away from Campbell on Thursday. But he was left with little choice but to use him.

“We had to push Campbell there,” said Cora. “We were running out of players. We did run out of players, but it is what it is. It was a tough one. I like the way we fight. We're there until the end. But obviously, it was a tough series, and we just have to turn the page.”