WEST SACRAMENTO, Calif. — The flourishing excitement of the six-game winning streak that began in Baltimore and continued to Seattle ground to an end in Sacramento, and it served as a reality check for an Orioles team attempting to make a comeback in the standings.

By no means do two losses against the Athletics — including Sunday’s 5-1 defeat — serve as a sign that a comeback is impossible. But the Orioles don’t have the luxury of missed opportunities, and the series against the Athletics was just that — a missed opportunity against a fellow struggling club.

Baltimore entered this road trip on the back of a sweep of the Chicago White Sox. The Orioles continued it with a sweep of the Mariners. Then they lost two of three to the Athletics, which somewhat dampens the fire around the club after it rattled off a half dozen wins.

“You go on the West Coast for six games, it’s tough,” interim manager Tony Mansolino said. “There’s issues with sleeping through the morning, everyone’s up at 6 a.m., the days are long, it’s hot, we haven’t been in the heat. You walk out of this thing 4-2 against a really good Seattle team and a Sacramento team ... I’ll take it.”

At its core was the small regression of the starting rotation, which was one of the main catalysts for Baltimore’s improvement. In three games at Sutter Health Park — which is hitter friendly — Dean Kremer, Charlie Morton and Tomoyuki Sugano combined to allow 12 runs in 12 innings.

But the offensive issues against left-handed pitching also reared their head once more Sunday. Left-hander Jacob Lopez, who entered with a 7.20 ERA in seven games, held Baltimore to one run in four innings. The Athletics kept the southpaws coming out of the bullpen, with Sean Newcomb pitching three scoreless innings and T.J. McFarland stranding a runner on second in the eighth.

The Orioles fell to 3-12 when facing a left-handed starter. Their teamwide on-base-plus-slugging percentage against lefties is .559 — the worst in the majors.

“The story’s just left-handed pitching again,” Mansolino said. “Left-handed pitching got us. We’ve got to figure it out.”

Mansolino hinted at “solutions down the pipeline,” and some of that involves the impending returns of injured players, such as Jordan Westburg, Tyler O’Neill and Gary Sánchez. The latter two were signed, in part, to help solve Baltimore’s issues against southpaws. That hasn’t been the case when healthy, though. O’Neill is hitting .087 against lefties. Sánchez is without a hit in 19 plate appearances against them.

“Just another game where we’ve seen left-handed pitching that shouldn’t beat us up did beat us up,” Mansolino said. “We’ve got to be better.”

The four runs (three earned) against Sugano in Sunday’s series finale were a departure from the success he’s produced for much of his first season in MLB. With 4 1/3 innings pitched, it was Sugano’s shortest outing since his debut in Toronto. The Athletics scattered eight hits off him, but the defense didn’t help matters.

The Athletics grabbed a lead through singles from Lawrence Butler and Tyler Soderstrom in the first, and they added three in the second inning, beginning with Jhonny Pereda’s RBI double. Emmanuel Rivera, playing first base, made the first mistake of the frame when he allowed a Denzel Clarke grounder to evade him.

It was initially ruled an error but became a single, because Rivera missed it entirely. And Butler, the next batter, drove in a run when his grounder took an odd hop off the mound and Gunnar Henderson bobbled it for an error at shortstop. Then Jacob Wilson, a constant thorn in the side of Orioles pitching this weekend, produced another RBI single.

“I was mainly trying to get groundouts, but [they] became hits,” Sugano said through team interpreter Yuto Sakurai. “They were hitting it pretty well, so I struggled a little bit at the beginning.”

And finally, after 20 2/3 scoreless innings pitched by Baltimore’s relievers during this road trip, Max Muncy greeted right-hander Bryan Baker in the eighth with a 431-foot homer.

If the Orioles win four of every six games they play from now until the trade deadline, as they did on this West Coast road trip, they’ll reach July 31 with a slightly above .500 record. In that case, general manager Mike Elias could decide to buy — or at least stand pat — rather than selling off expiring contracts.

But to maintain that strong pace — required to climb out of what was, at worst, an 18-below-.500 hole and is now only 26-38 — the Orioles will need to take advantage of matchups against fellow bottom feeders. Instead, in Sacramento, Baltimore was reminded that a recovery from this position will be no easy task.

“You sit at your locker, you kind of sit on it for a minute and it’s on to the next series,” said infielder Coby Mayo, who impressed with a line-drive single at the end of a nine-pitch plate appearance. “If you’re worrying about this past series or the series before that, you’re going to find yourself not worrying about what’s in front of you. And obviously you’ve got a really good team coming into town on Tuesday.”

He’s right. Next up are the Detroit Tigers, who swept the Orioles this season and who boast the best record in baseball (43-24). In a season as long as this one — and in a hole as large as this one — the mind must always be on to the next game.

This article has been updated.