SEATTLE — The span of half innings summed so much of what has plagued the Mariners in their worst moments of 2017.

That they came in the bottom of the first and the top of the second inning in Monday’s 11-3 loss to the Orioles, well, it just made the next seven innings a frustrating formality.

And now they’ve lost five straight games at home, falling to 59-61 and 2 1/2 games back in the wild card, trailing three teams, including the Orioles who passed them.

“Obviously we have not played well the last five games at home for a number of different reasons,” manager Scott Servais said.

Maybe playing only seven home games in August isn’t such a lamentable situation for Seattle, because right now they are playing some of their worst baseball of the season at the worst possible time.

The issue didn’t start in the top of the first. Yes, starter Yovani Gallardo put the Mariners down a run on his first pitch of the game — a 91 mph fastball that split the plate. The get-me-over strike was ambushed by Baltimore leadoff hitter Tim Beckham for his first career leadoff home run. Still, a 1-0 deficit in the top of the first could be easily matched or overcome.

That’s what made the bottom of the first so important. The Mariners needed two batters to render that run moot. Jean Segura led off the game with a double to right field off Baltimore starter Kevin Gausman. Yonder Alonso followed with a double over the head of center fielder Adam Jones to make it 1-1. The Mariners seemed poised for a big inning when Robinson Cano singled to right and a baserunning misread by Alonso was offset by a silly throwing error from Beckham. It gave the Mariners runners on second and third with no outs.

The “crooked number” that teams crave loomed.

But Seattle never capitalized.

Nelson Cruz, the team’s hottest hitter coming into the game, struck out swinging. Kyle Seager struck out swinging and Guillermo Heredia grounded out to end the frame.

It was a wasted run-scoring opportunity for a team that understands it needs every run possible with its current pitching situation.

“We got one and that’s when starters are vulnerable,” Servais said. “The game kind of got out of hand after that.”

Indeed, Gallardo then produced an interminable top of the second that saw the Orioles score six runs and put the game essentially out of reach.

After retiring Trey Mancini to start the inning, Gallardo served up back-to-back doubles to Mark Trumbo and Chris Davis that led to a run. Davis’ long fly ball to left was just out of the reach of a leaping Heredia. It’s a tough play, but one that he’s made during the season on several occasions. But it’s also the type of run-prevention play that hasn’t been made by the Mariners of late. Instead of an out, it was a run.

And then it started to get messy.

Former Mariner Seth Smith, who was traded for Gallardo, singled to left, putting runners on first and third. A double play could still limit the damage, particularly with catcher Caleb Joseph coming to the plate. Gallardo induced the ground ball, but didn’t get an out. It was a slow roller to third that Seager fielded on the run and threw home instead of to first. Davis slid under the tag to make it 3-1.

The downward spiral continued.

A single from Beckham to right field loaded the bases for Manny Machado, something that isn’t good, despite his down season. Gallardo fell behind in the count and left a 2-1 fastball belt high on the inside part of the plate. Machado couldn’t swing at the mistake pitch fast enough, sending a vapor trail into the upper deck in left center. The grand slam made it 7-1.

“I’m sure he was fired up a little bit,” Servais said. “That was the club he played with last year. I thought his stuff and his fastball velocity-wise was as good as we’ve seen in a while. But sometimes he was overthrowing. We saw a lot of hard stuff and didn’t see the back and forth with the changeup. It was predominantly all hard and they got on it.”

Gallardo limited the damage to just six runs in the inning, eventually striking out Trumbo two batters later. Besides the six runs, the Orioles had six in the frame with Gallardo throwing 50 pitches. Yes, 50.

The Mariners received a sarcastic cheer from the 17,973 fans in attendance — it was still too early in the game to beat traffic.

To Gallardo’s credit, he went on to throw 99 pitches to save on bullpen arms. It was the 48th time this season a Mariners’ starter failed to pitch beyond five complete innings — a number that figures to grow.

The Mariners’ other runs came via solo homers. Mike Zunino crushed his 18th and Cruz continued his push toward a fourth straight 40-homer season, belting homer No. 29.

Perhaps the most entertaining aspect of the night for the Mariners was the big-league debut of fireballer Thyago Vieira. He entered the game in the top of the ninth. His first pitch — a 98 mph fastball — was sent back at his face but he was able to catch the rocket for the first out.

“Line drives don’t scare me,” he said. “It’s baseball. You have to be prepared for everything.”

Vieira struck out Joey Rickard on a nasty slider and then got a ground out for a clean inning.