PHILADELPHIA -- George Kirby was the losing pitcher on Thursday despite throwing the entirety of the Mariners’ 1-0 defeat to the Phillies. It was a career day for Seattle’s second-year standout, but he was plagued by a lack of run support in the club’s second shutout of the season.

Kirby cleared the eighth inning for the first time in his pro career, and first since throwing what he estimates four or five complete games at Elon University, before the club took him in the first round of the 2019 Draft. 

More encouraging was the fortification of his breaking balls, which he said were among the best he’s ever thrown. That alone represents a significant development given that they weren’t generating much swing-and-miss over his first four outings in 2023. 

All told, he threw just 89 pitches, surrendered four hits, one walk and one run, but it proved decisive. He’s credited with a complete game, but one of the unfortunate shorter-than-nine-innings variety, which always indicates a loss unless it's a weather-shortened game.

“I thought I pitched great,” Kirby said. “I threw a lot of good curveballs, kept them off balance all day and did my job for as long as I could.”

Kirby generated 13 whiffs, a mark he’s reached six times in 30 career starts, and surrendered just five hard-hit balls (anything 95 mph or higher) among the 20 in play against him.

“Some days, it's like you're just unconscious, just throwing out there,” Kirby said. “Everything felt good.”

Kirby now has the highest K/BB ratio (6.54) through a pitcher’s first 30 career starts in AL/NL history.

The lone run scored via a hit-and-run with two outs in the second inning on a line drive into the right-center gap that ended with Julio Rodríguez sailing an 87.4 mph throw to first baseman Ty France just behind the mound. During the bang-bang play, Nick Castellanos, who took off during Kirby’s windup, scored all the way from first. 

Had the throw been to second baseman Jose Caballero in shallow center, there might’ve been a play at second base or the plate, or Castellanos might not have attempted to score.

"It doesn't show up as an error or anything like that, but it's a mistake, and it cost us a run, ultimately the game-winning run,” Mariners manager Scott Servais said. “He's got to hit the cut-off man."

Rodríguez was also among Seattle’s quiet bats, going 0-for-4 Thursday after striking out four times Wednesday, though he did hit his fifth homer in that contest. The Mariners mustered just five baserunners and only reached second base three times, after which they went 0-for-5 with runners in scoring position. 

Tom Murphy was the lone bright spot offensively, going 2-for-3 with a double. He also had a hard-hit lineout that Castellanos caught sliding, robbing them of a chance to score in the eighth. He capped the day with an impressive caught stealing that ended the eighth inning and allowed Kirby to go the distance.

“It feels good to be able to go out there and contribute and everything,” Murphy said. “Kirby was the master of that game for sure though, and that's one you want to score a couple of runs for that guy.”

The late-inning magic that’s been ingrained in Seattle’s fabric the past two years has mostly eluded the club so far this season, as has its success in tight games. The Mariners fell to 3-7 in one-run games after leading MLB with 67 victories in such games the past two years combined. 

"Three hits ain't gonna get it done -- not in this ballpark, not against anybody,” Servais said.

Seattle's struggles against lefty pitching has also been a prominent factor. The Mariners entered the day hitting .206/.269/.382 against southpaws for a .651 OPS that ranked sixth-worst in MLB, and then proceeded to go 2-for-18 against the Phillies’ Matt Strahm, who was pulled after 5 1/3 innings out of precaution due to his slow build-up after pivoting to Philly’s rotation late in Spring Training.

Making the loss sting more was that it came 24 hours after the Mariners blew Wednesday’s lead in the eighth inning, their 11th defeat this year in a game in which they led -- tied with Oakland for the most in MLB. 

Thursday marked Kirby’s longest start since throwing seven shutout innings in Game 3 of last year’s American League Division Series against Houston, the 18-inning marathon that ended with the same score as Thursday.

“I know he's disappointed we didn’t win the ballgame,” Servais said. “He feels bad, but he absolutely did his job.”