BALTIMORE -- On paper, Sunday’s matchup between George Kirby and Corbin Burnes looked like it would be among the day’s best pitching duels. But after Kirby was ambushed by two homers, two doubles and a career-high 10 balls ripped over 100 mph, the Mariners were playing catch-up all afternoon in a 6-3 loss at Oriole Park.

Seattle made things interesting in the seventh, once the O’s dipped into their leaky bullpen. But the Mariners were only able to come away with two runs, after Josh Rojas hit into a double play -- with shortstop Gunnar Henderson barely keeping his shoestrings on the bag during the exchange -- and Cal Raleigh hit a 368-foot flyout that might’ve been a sac fly.

Mariners manager Scott Servais considered challenging the double play, but replay review indeed revealed that Henderson completed the play by inches. It was one last gut punch that Baltimore’s blossoming shortstop landed over a weekend in which he crushed a homer in all three games -- including a leadoff blast off Kirby on Sunday, which extended his MLB lead to 15.

Henderson sat on a splitter low-and-in in a 1-2 count, then Ryan O’Hearn took Kirby deep on an 0-1 fastball up-and-in two innings later.

“I just didn't execute my pitches,” Kirby said. “Early on, the sinker, it was moving. I just wasn't getting it in the right spots, kind of leaving it down the plate. I wasn't really making them uncomfortable, either. They were just kind of getting their swing off.”

Most pitchers are most susceptible in the first inning, but that’s been particularly true for Kirby, who has a 6.30 ERA in the opening frame across 10 starts -- well above the 4.27 league average and his 3.70 mark over his first two seasons. This year, he has a 3.50 ERA in all other frames combined.

“When teams do get to George, it usually happens early in the game and early in counts, and that's what we saw today,” Servais said.

What adjustments can he make?

“When you have that kind of fastball -- and George is a fastball pitcher, there's no question about that -- but the other team knows that as well,” Servais said. “So in early games, you really have to locate it, and if you miss location, and they're on your fastball timing, they got some barrels to it today.”

Henderson backed that assertion, saying: “I know he's got a good heater, so just trying to get something out over, and I felt like I saw it pretty well out of hand."

Kirby wound up settling in after the third, retiring 10 of his final 11 batters and each of his final eight to clear the sixth inning. The biggest tweak he made was changing the grip on his sinker, which led to four of those outs, as he threw that pitch more regularly (37%) than any of his 83. But he virtually abandoned the splitter after Henderson’s homer.

“That pitch recently for me, it hasn't felt good in my hand,” Kirby said. “So I've just got to tweak that a little bit.”

The sinker has been an elite ground-ball pitch, as opponents have just a .155 batting average against it. But Kirby was forced to go to it more because he lacked whiffs within the rest of his arsenal, with just a combined four in the first three innings.

How can he adjust to keep hitters off the barrel in those instances?

“Just kind of really being fine with the sweeper, especially to some righties,” Kirby said. “Later in the game, I started some swings and misses, just starting on the plate and kind of down. I kind of started [the outing] in on them, moving it towards the middle, which is not good.”

Kirby can take solace in finishing strong, but the beginning put Seattle’s bats in too big of a hole -- especially against former Cy Young Award winner Burnes, who matched a season high with 11 strikeouts and K’d everyone in the Mariners’ lineup except Luke Raley.

Kirby departed with the Mariners trailing by four runs, a mark they’ve yet to overcome this season. They fell to 0-12 when falling behind by that many, and only thrice last year were able to mount a comeback of that size.

Now, they head to Yankee Stadium, where the team with the best record (33-15) in the American League awaits.