SEATTLE -- The way that Logan Gilbert was cruising on Tuesday night, it looked for a while that maybe one run of support would be all he’d need.

But after laboring into traffic in the seventh inning -- then nearly escaping it -- Seattle’s towering righty paid mightily for a middle-in slider that Nelson Velázquez blasted for a three-run homer. And with the Mariners manufacturing just two runs, via solo homers from Mitch Haniger and red-hot Luke Raley, Gilbert’s fateful moment wound up being the defining one in Seattle’s 4-2 loss to Kansas City at T-Mobile Park.

“We lost, so it didn't feel very good, and the home run was a big part of that,” Gilbert said. “So I’ve got to be better. For the most part, I felt like I threw the ball good, but I made a couple of mistakes, and those are the ones that mattered.”

It was a sour finish to an otherwise dominant outing, as Gilbert had allowed just four baserunners through the sixth. But two walks in the seventh -- one over eight pitches from leadoff man Bobby Witt Jr. and another intentionally to Salvador Perez after falling behind 3-0 -- wound up being arguably as costly as the 398-foot blast from Velázquez, whom Gilbert had struck out twice.

Also costly was a bobbled exchange by second baseman Josh Rojas just prior, which put Witt on second base when Rojas’ only play was to first for the first out instead of leading to Gilbert’s third double play. Given that Kansas City veteran Michael Wacha was also on cruise control by masterfully mixing speeds, any traffic loomed large.

“I don't know if it's frustrating, just disappointing,” Mariners manager Scott Servais said. “You know what I mean? You can't pitch any better than he did. You really can't. Certainly, the top of their lineup, they've got firepower.”

Gilbert was relieved just after the homer, which was pummeled on his 99th pitch. An inning later, Trent Thornton issued a leadoff walk to Hunter Renfroe, then surrendered an RBI single to Maikel Garcia that gave the Royals the cushion they needed.

Over his past two outings, including an eight-run loss at Minnesota last Thursday, Gilbert has seen his ERA rise from 1.69 to 3.07. He’s been most susceptible with runners in scoring position, as opposing hitters now have a .923 OPS in 30 plate appearances in such situations, well above the .741 league average. Conversely, batters have just a .550 OPS with the bases empty.

“To win a 1-0 game, 2-0, 2-1, something like that,” Servais said, “you've got to make every play and not give them any extra outs. ... Logan had all those things going for him that allowed him to get deep in the game like that. We just didn't finish it off there in the seventh.”

The Mariners, meanwhile, only had two runners reach scoring position. Julio Rodríguez went first to third on a two-out single from Ty France in the eighth, but Cal Raleigh struck out swinging as the tying run to halt the rally. And before that, they hadn’t reached second base since Josh Rojas advanced there on a wild pitch back in the third, after drawing a walk.

For as stinging as Gilbert’s ending was, two runs were never going to be enough -- and the second didn’t manifest until the Mariners had only two outs to work with, when Haniger went yard in the bottom of the ninth.

Seattle is now 2-14 when plating that few. It is averaging 5.3 runs per game in 23 wins but only 2.1 in its 20 losses.

The club was also without Jorge Polanco, nursing right hamstring tightness he suffered in Monday’s win, and Mitch Garver, who’d been swinging much better in May before being scratched with upper back spasms 45 minutes before first pitch. It’s a different issue than the lower back pain that sidelined Garver for three games just after Opening Day.

The Mariners still have a chance to win their eighth series of their past nine in Wednesday’s finale. And the Royals are much improved, matching their entire first-half win total from 2023 with their 26th victory of '24 on Tuesday, two months before the All-Star break.

But given the gem that Gilbert was spinning, Tuesday’s defeat simmered a little more.