PHOENIX — Zac Gallen bit his glove. He knew he was almost out of the jam — and really should’ve been out of the jam — if his second baseman hadn’t bobbled the ground ball from Cedric Mullins.

Gallen instead crouched behind the mound at Chase Field after Arizona Diamondbacks second baseman Tim Tawa settled for an out at first rather than being able to turn two. It was the sort of break for which this Orioles offense has been waiting.

The Orioles entered Monday’s game against the Diamondbacks with an uneven offensive series in Kansas City just behind them. In two losses, Baltimore combined for three runs. But that bobble from Tawa kept the fifth inning going, and Ryan Mountcastle turned that chance into a crooked number.

Mountcastle’s single — which came on a slider from Gallen that was just 0.97 feet above the ground, according to Statcast — drove in an extra two runs in an inning that might’ve ended with the bases loaded. It chased Gallen from the outing and it provided the Orioles with a healthy lead to hold behind right-hander Zach Eflin’s gem.

“I feel like we had traffic all night,” right fielder Ryan O’Hearn said. “Guys were just getting on base, and then eventually, a big hit with Mounty. Guys had good at-bats, found ways to get on base and it ended up in runs.”

The 5-1 victory Monday might have been the most complete performance from Baltimore this season. While it has only been 11 games, those 11 games have been filled with short starts, a patchy offense and a lack of spark. Eflin dispensed with the first of those issues by completing six innings. The offense took advantage of a mistake to plate three runs in the fifth. And Gunnar Henderson, playing his fourth game since returning from a rib injury, looked like Gunnar Henderson should.

Before the game, sitting at his locker within the visiting clubhouse, O’Hearn waved off any concerns around the offense. It’s too early to panic, he said, and then O’Hearn went out and blasted a solo home run off Gallen to start the Orioles off.

“I’ve had some days where I hit the ball good and didn’t get any results,” O’Hearn said. “I’ve had some days where I felt like I’m swinging at everything and wasn’t having good at-bats. So, just kind of flushing those days, no matter what it was, good or bad, and showing up the next day and trying to figure it out. Just staying even-keeled. I know what I’m capable of. Nice to get a homer tonight and have some good at-bats and get the win.”

Henderson and Adley Rutschman combined in the third with two straight rockets off the bat that traveled with an exit velocity of 106.3 mph. Henderson, with his first double since returning, scored on Rutschman’s single.

And in the fifth, Baltimore gave Eflin more room to work. The Orioles loaded the bases with one out, and while Mullins’ grounder might have ended the inning, it turned into an RBI. Mountcastle dug out a two-run single next, and the pitching staff cruised from there.

Before the game, manager Brandon Hyde said he hoped for longer outings from his starters. Eflin was doing a sublime job of that — he finished the sixth inning at 73 pitches and had just retired eight batters in a row. But Hyde said after the game that the righty did not come back for the seventh inning due to shoulder fatigue.

“We’re going to get some tests done and we’ll hopefully keep our fingers crossed that everything’s OK there, because he was absolutely cruising and so efficient and throwing the ball to both sides of the plate,” Hyde said. “We’re hoping for the best tomorrow.”

Eflin added that he’s “pretty optimistic, but we’ll see how it feels tomorrow.” Last year, Eflin had a brief stint on the injured list due to shoulder inflammation.

The early pull of Eflin prompted the Orioles to turn to right-hander Yennier Cano in the seventh. By using Cano on consecutive days, Hyde ensured the reliever won’t be available Tuesday (early in the year, he stays away from pitchers on three consecutive days by rule). Employing right-hander Félix Bautista in the ninth inning without a save situation means Bautista won’t be available, either.

And with right-hander Charlie Morton pitching tomorrow, there may be need for the bullpen.

The trickle down of Eflin’s early exit remains to be seen. What is known is that for a third straight start, Eflin completed six innings, and he did so Monday with only four whiffs. For what he lacked in swing-and-miss stuff, Eflin made up for it with seven groundouts. And he eluded early hard contact against him to provide another quality start.

“Today was a day where I was getting early contact when I was throwing strikes, getting ahead of guys, and that’s what’s going to keep you deep into the game,” Eflin said. “But, you know, there are obviously certain situations where you need strikeouts and I’m fully prepared for those, but I’m not a strikeout chaser, I’m an out chaser.”

With Eflin and an offense that took advantage of a bobbled ball, the series opener in Phoenix became an all-around strong showing. Baltimore has yet to win consecutive games, though. For as positive as Monday night became, the next challenge will be extending that positivity for two nights and more.

“I think when the offense starts rolling and you get three or four guys hot at one time, that’s how you rattle off a bunch of wins,” O’Hearn said. “Knock on wood, I feel like we’re on the cusp of that.”