NEW YORK -- The Red Sox have their starting rotation back on track and the offense has been much better of late following a recent dip.

But what about the bullpen?

That continues to be a source of stress, and it looms as an issue that threatens to keep the Red Sox out of the playoffs if it doesn’t get fixed soon.

In a 5-3 loss to the Yankees in Game 1 of a day-night doubleheader Tuesday, manager Alex Cora again couldn’t find relief when he pulled his starter.

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“We’ve got to attack guys and put them away. There’s too many deep counts,” said Cora. “We’ve been walking a lot of people. We’ve just got to be better in those situations.”

Starter Tanner Houck had thrown 58 pitches through four innings while giving up two runs. In a nine-inning game, Boston’s No. 6 prospect would have been a no-brainer to come back for the fifth.

But Cora, mindful of the seven-inning rule for doubleheaders, was aggressive. And the relievers he entrusted didn’t come through in a back-breaking fifth inning.

First, Cora went to Garrett Whitlock, his most consistent reliever this season. Whitlock struck out DJ LeMahieu before walking two straight batters and gave way to Josh Taylor, who has been nasty against lefties all season.

However, Taylor didn’t do his job against Joey Gallo, walking him to load the bases with one out.

The Yankees then got some good fortune, as Luke Voit blooped in a single over the head -- and just out of the reach -- of second baseman Kiké Hernández. Hunter Renfroe, making his third career start in center field, wasn’t close enough to make a play. The two-run single gave the Yankees the lead back after Boston had moved in front on a solo homer by Christian Vázquez in the top of the fifth.

“That was a tough fifth inning,” Cora said. “Tanner gave us four. Where we were bullpen-wise and matchup-wise, we felt Whit can go through the fifth, and then J.T. in the sixth against some of those lefties. But we ended up walking Gardner and Judge.

“It felt like J.T. was a good matchup against Gallo and Voit actually. We went to him, he walked Gallo and then the bloop single. At the end of the day, that’s what they do -- they control the strike zone, they don’t chase too many pitches. The walks today put us in a bad spot.”

In the last 12 games dating to Aug. 5, Boston’s bullpen has an 8.31 ERA, allowing 36 earned runs in 39 innings. Over that same stretch, the ‘pen has been hit to the tune of a .317 batting average and a .929 OPS while walking 26 and striking out 44.

How much of a regression is this?

In the 109 games that preceded Aug. 5, the bullpen had a 3.57 ERA while holding the opposition to a .238 batting average and a .708 OPS.

Other than Darwinzon Hernandez, who is on the injured list, every pitcher who contributed to that strong four-month stretch is still on the active roster.

“Yeah, it hasn’t been great, but we still have good stuff,” Cora said of the recent fade in the ‘pen. “We’ve got to make sure we get ahead of guys and put them away. That’s very important for us.”

With 41 games left in the season, mission No. 1 for the Red Sox will be to get the bullpen back in working order.

“We’re in August,” said Vázquez. “It’s a tough month for a bullpen, for everybody. It’s a lot of games in the bank for everybody and we need to keep grinding and keep grinding and keep playing baseball. This is a marathon. This is not a sprint. We need to keep going, keep pitching and get the team together and get back on track like a team.”