SEATTLE -- George Kirby wanted it back immediately out of his hand. 

Seattle’s blossoming starting pitcher had exercised the pinpoint command of his repertoire against a division rival he’ll see for years to come, putting more Major League credibility to the scouting reports that raved about his four-pitch arsenal as a Top 100 prospect.

But sometimes, especially for a pitcher, the baseball doesn’t behave the way you want. Such was the case when Kirby dropped in a 95.3 mph four-seam fastball at the bottom of the zone in his second matchup with Mike Trout, who punched it into the right-field seats for a two-run homer. 

Kirby zeroed back in and was scoreless the rest of the way, going toe to toe with the Angels’ other superstar, Shohei Ohtani, in a classic pitchers' duel. But with the Mariners’ offense stumbling again, Kirby’s lone mistake proved decisive in a 4-1 loss that opened a five-game series at T-Mobile Park on Thursday.

• Box score

“I felt great,” Kirby said. “I threw my curveball really well today. My changeup, great; fastball, great. My slider was a little off, but I made one mistake to Trout and stuff happens. I was trying to go up. It hasn’t been going my way so far. So, I’m hoping they make a mistake when I do. I’ve just got to be myself and attack the zone.”

Seattle’s first-round Draft pick in 2019, Kirby lowered his ERA to 3.56 in his eighth outing, the second-best mark among qualified AL rookie starters. He threw six innings, struck out six and surrendered five other hits beyond Trout’s homer. Moreover, he walked just one -- also Trout, in his first plate appearance -- which represented one of just two three-ball counts.

Therein lies the micro learning experience in this single start within the macro picture of his season. Kirby exclusively threw elevated fastballs to Trout in that five-pitch free pass in the first inning, missed the one in his second plate appearance that landed in the seats, then came back in his final matchup with the three-time MVP and struck him out on a high heater.

• Sign up for the Mariners' Beat newsletter

It wasn’t exactly a defining moment of resiliency, especially given the game outcome, but it underscored a young pitcher having a gameplan against one of the best players on the planet and being able to flush away a costly mistake and execute.

“I thought I pitched really well all six innings,” Kirby said. “I just made one mistake. I’m just taking every [start] as a learned lesson. I’m trying to learn something from each start and go attack the guys the next time I go out there. I’ve just got to be aggressive and stay ahead, and when I do that, I do really well.”

The Trout punchout was punctuated by one of a career-high 16 swings-and-misses that Kirby generated, 12 of which came on his four-seamer, which was up a half-tick from his season average, to 95.5 mph, while topping out at 97.8 mph. Yet he had a healthy mix among his changeup, curveball and slider, too, which was on display when he struck out the side in the second inning, each on a different pitch.

“He continues to learn and get better every time out there,” Mariners manager Scott Servais said. “Using probably 50 percent fastballs and 50 percent offspeed [a combination of the slider, curveball and changeup] is probably the most ideal number for him. Some nights it might be more or weighted one way or the other, but an outstanding job tonight.”

Unfortunately for Kirby, Ohtani was as effective, matching Kirby’s six innings and going scoreless. The Halos’ two-way star went with a slider-heavy attack -- using it more than any pitch -- and doing so effectively. The Mariners put six balls in play against it, but only one for a hit, an 89.1 mph single by Adam Frazier in the second.

Ohtani simply didn’t give the Mariners much to hit and also had a fastball in his back pocket that topped out at 99.4 mph, which he used for a pair of his six strikeouts. It was the last recipe a struggling offense needed, especially as it began the first of eight games against these division rivals over these next two weekends.

The Mariners had some traffic in the eighth inning, after Ohtani departed, when J.P. Crawford lined an RBI double into the right-field corner that scored Dylan Moore all the way from first base. But after Trout homered again in the seventh, off Sergio Romo, the Angels -- who had lost 18 of 20 coming into this one -- had all the cushion they needed.

Meanwhile, Mariners starting pitchers, including Kirby, have been on a tear, with a 2.78 ERA over Seattle’s past 20 games. But the club overall is .500, in huge part to the offense coming up short.