Kansas City's Stephen Kolek dominates Mariners with complete-game shutout

KANSAS CITY, Mo. - With their well-documented and much-debated struggles against left-handed pitching, featuring a passel of right-handed swinging platoon hitters that have severely underperformed in their role, the Mariners are almost always happy when an opponent starts a right-hander against them.

But what if it's a right-hander who is actually tougher against left-handed hitters? Should they still be excited? Perhaps not.

Right-hander Stephen Kolek, who has reverse splits and has actually been tougher against left-handed hitters, delivered the best outing of his career against a Mariners lineup featuring six left-handed hitters Saturday afternoon at Kauffman Stadium.

Kolek held the Mariners scoreless over nine innings, allowing four hits with a walk and two strikeouts, while becoming the fourth pitcher in Major League Baseball this season to toss a complete-game shutout, in the Royals' 5-0 victory.

Kolek's performance helped end a four-game losing streak for his team. It was just the second win for the Royals in their last 12 games.

Tough one this afternoon, especially coming off the win last night," manager Dan Wilson said.

It was the sixth time this season the Mariners have been held scoreless. That number somehow feels low given their overall inconsistency at the plate. They have scored two runs or fewer 19 games this season. Remember, this was the Mariners' 53rd game of the season. Seattle is 2-17 in those games.

"Kolek made it difficult offensively for us to get base runners or to get anything going on offense," Wilson said. "His off-speed stuff was good, and he had a good changeup. He just moved it around and made pitches. You don't see complete games often."

Kolek, who pitched in the Mariners farm system for three seasons (2021-23), had made just three starts this season after suffering an oblique strain in spring training.

In that small sample size, he has been more effective against left-handed hitters thanks to a nasty changeup that runs away from lefty hitters, who just can't seem to put it on the barrel. The reverse splits are distinct:

This season vs. right-handed hitters: 19 plate appearances, .294/.368/.647 slash line, seven runs allowed, five hits, two homers, a walk and a strikeout.

This season vs. left-handed hitters: 50 plate appearances, .170/.220/.255 slash line, one run allowed, eight hits, a double, a homer, three walks and 11 strikeouts.

But it isn't just that small sample size. Since being traded from the Padres to the Royals on Aug. 30, Kolek has held left-handers to a .148/.194/.221 slash line in 122 plate appearances and a .242/.277/.419 slash line (15-for-62) against opposing righties. He's been slightly more effective against lefties for most of his career:

Career vs. right-handed hitters: 348 plate appearances, .274/.323/.383 slash line, eight homers, 16 walks, 54 strikeouts.

Career vs. left-handed hitters: 393 plate appearances, .231/.296/.344 slash line, eight homers, 31 walks, 74 strikeouts.

But is that data enough for Wilson to roll out his much-maligned right-handed hitting lineup featuring Rob Refsnyder and now Patrick Wisdom and Victor Robles against a right-handed pitcher? Not unless he was masochist or wanted to see the app formally known as Twitter implode in anger.

But really, it didn't matter against the Mariners. Kolek was effective against everyone in the lineup except Luke Raley, who had three of their four hits against him.

Late last season, Kolek pitched 7 1/3 innings against the Mariners, allowing two runs (one earned) on two hits with a walk and eight strikeouts. One of his runs allowed came on a replay appeal of Michael Massey violating the shift rules and having his heels on the outfield grass when the pitch was delivered.

"I was keeping an unofficial tally," Royals manager Matt Quatraro said. "I think it was 10 or 11 ground-ball outs. It's just what we've seen. Attack and keep them on their heels, get soft contact."

The Mariners best chance to score off Kolek came in the second inning. Raley reached on an infield single and advanced to third on Cole Young's single to right field. With runners on the corners, Dom Canzone hit a ground ball to the first base bag. Vinnie Pasquantino gloved it, stepped on the base and fired home. Raley had taken off toward home thinking Pasquantino might fire to second to turn a double play. The Royals got the double play a different way. The throw to home was well ahead of Raley, who stopped and tried to retreat to third but was tagged out.

"With a guy on first, you want them to try and turn the double play," Wilson said. "On something like that, it's a trickier read and you probably want to stay (at third) there."

The Mariners got an uneven start from George Kirby and some sloppy play in the field to put them down 3-0 in the first inning.

Maikel Garcia led off with a double. Bobby Witt Jr. followed with a slow roller to third for an infield single as Garcia advanced to third. Seattle made a costly error on Pasquantino's ground ball up the middle. Young fielded it moving toward second, but an awkward underhand toss to J.P. Crawford was bobbled allowing a run to score and Witt to slide in safely. Both runners moved up 90 feet on a double steal. After getting Salvador Perez to ground out softly in the infield without allowing a run to score, Kirby gave up a bouncing ball to the right side of the infield. Josh Naylor fielded it moving away from the base. Kirby didn't cover on the play. Young raced over from second and was there, but Naylor opted to sprint to the base instead. Seeing that, Witt, one of the fastest runners in baseball, raced home for a 2-0 lead. Jac Caglianone made it 3-0 on ground ball single just past the diving Young.

"George deserved a better fate," Wilson said. "That first inning, a lot of soft contact with a couple of miscues on our part. We weren't able to get him out of it there without the three runs of damage."

Kirby made it through six innings, giving up five runs (three earned) on a season-high nine hits with no walks and three strikeouts.

Over his last two outings, he's pitched a combined 11 ⅔ innings, allowing 11 runs (nine earned) on 15 hits with two walks and nine strikeouts.

"Even after the game, I can't really ask for much more," Kirby said of the weak contact and ground balls allowed. "Maybe some more swing and miss would have been nice, but like I'm doing my job, getting weak contact, and sometimes, yeah, it just doesn't go your way. So you've just got to keep (expletive) going.

BOX SCORE

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This story was originally published May 23, 2026 at 4:51 PM.