SEATTLE -- Yusei Kikuchi put all of his weapons on display Friday and put backing to the Mariners’ assertion that he could be on the cusp of a big season.

But one heater to Evan Longoria that caught a little too much plate led to a two-run homer that tied the game. The following inning after Kikuchi left, new Seattle reliever Drew Steckenrider gave up three runs that gave San Francisco enough cushion in a 6-3 win Friday at T-Mobile Park.

• Box score

Yet the good from Friday: Kikuchi threw 67 of his 89 pitches for strikes (75.3%) -- his second-highest rate in any of his career 42 starts and well above his average of 63.5% from 2019-20. Even better, he threw 19 first-pitch strikes among the 25 batters he faced for a career-best rate of 76% -- significantly higher than his 57.3% average in 0-0 counts over his first two seasons.

Kikuchi also achieved these developments with a more credible litmus test than his solid Spring Training outings. He struck out a career-high-tying 10 batters Friday and showed elite spin and velocity on his four-seam fastball, dialing it up to 97.4 mph and averaging 2,415 RPM, well above his 2,111 RPM average over his first two big league seasons. More spin tends to lead to more swing and miss, and five of his strikeouts came on his heater.

If this sounds like a data dump, here is a breakdown of his six innings against the Giants:

And an illustration of Kikuchi’s improved location over his first two seasons:

In the eyes of the Mariners, the accuracy of Kikuchi’s pitches -- and his ability to overcome mid-inning challenges, as he did in a 24-pitch fourth -- are huge improvements.

“That's as dominant an outing as we've seen him have,” Mariners manager Scott Servais said. “Really happy and looking forward to seeing many more outings like that this year. Big confidence booster for him getting off to a good start.”

The often quiet and cerebral Kikuchi even exuded quite a bit of emotion after a few of his punchouts, more than he had in any start in recent memory. It was perhaps a reflection of the confidence and self-trust that he has gained after 41 starts in his first two years that yielded up-and-down results: an 8-15 record, 5.39 ERA, 1.47 WHIP, 10.2 hits per nine innings and 1.7 homers per nine.

“All spring, I was told from [pitching coach Pete Woodworth] and Skip and everyone about just being aggressive in the zone and just attacking the zone,” Kikuchi said through an interpreter. “And I think that's something I was able to do today. … I just have a lot more confidence in all my pitches, and just have that mentality of being aggressive; I think that my emotions just kind of carried over from having that aggressive mentality. And I look to pitch with that aggression all year this year.”

The one pitch that Kikuchi would’ve liked to have back was one that kept him from leaving with a lead. What was more an impressive piece of hitting by Longoria than a mistake by Kikuchi led to Longoria’s second homer of the series, evening the score at 3. Kikuchi also gave up a homer to Buster Posey on a first-pitch fastball in the third inning.

The Mariners’ bats had their challenges against Giants starter Johnny Cueto, who kept Seattle honest all night by drastically altering his delivery mechanics over 105 pitches in 5 2/3 innings. But Luis Torrens and Evan White combined to drive in three runs against the two-time All-Star which gave the Mariners -- and Kikuchi -- a sixth-inning lead.

The more pronounced downside from Friday: The bullpen that posted an American League-worst 5.92 ERA last season was the culprit in Seattle’s defeat -- and a newcomer was on the hill when the damage was done. Steckenrider struggled to locate his fastball, which in turn kept him from establishing his secondary pitches. The hard-throwing righty, whom the club signed to a Minor League deal on Nov. 20, gave up three runs on two hits and two walks, with two strikeouts against the six batters that he faced, failing to get out of the seventh inning.

“Of all the relievers that we have in the bullpen, he probably has the most experience of anybody,” Servais said of Steckenrider, who pitched in 123 games for the Marlins from 2017-19. “But it's controlling the zone and we didn't do it. … We liked the matchup with him as the right spot to get him in the game, he just couldn't finish off the inning.”