Mathews soaks up MLB debut atmosphere ... well, what he can remember of it

TORONTO -- As a young club, the Cardinals have seen plenty of Major League debuts lately. Saturday at Rogers Centre, however, felt a little different when Quinn Mathews took the mound.

The lanky left-hander, whose contract was selected from Triple-A Memphis earlier in the day, carried himself with confidence as he went to work in Saturday’s 5-1 loss to the Blue Jays. Mathews immediately showed off a riding fastball and sharp slider, even if the details of those opening innings quickly became a blur.

“I can tell you what the third inning feels like,” Mathews said, smiling. “I don't really remember the first two innings all that well, if I'm being honest.”

The Blue Jays love to battle at the plate, ranking third in MLB with a 19.4% strikeout rate entering Saturday. Still, Mathews attacked the zone aggressively, twitching his front foot before unloading into his fierce delivery. He whiffed Kazuma Okamoto with a fastball in the first inning for his first Major League strikeout.

That pitch, at least, Mathews remembers. He plans to send the ball home to his family for safekeeping. Much of everything else was swallowed up by the emotion of pitching in front of a sold-out Major League crowd for the first time, with his family having flown in from Southern California to watch.

“It was unbelievable,” said Mathews. “I've never really experienced that feeling. I don't remember the first two innings of the game … it was almost like going numb.”

There was a lot to appreciate from Mathews’ debut. He worked five-plus innings, yielding two earned runs on six hits, along with three walks and three strikeouts. The stuff sizzled at times, and in the end, the 25-year-old found a respectable middle ground, working into the sixth inning before getting the hook.

Cardinals manager Oliver Marmol liked what he saw from Mathews, particularly his ability to escape trouble after allowing the leadoff hitter to reach in five of six innings.

“That’s where, [for] young dudes, it speeds up,” Marmol said, praising Mathews’ composure. “And it’s easy to throw a crooked number on him there. He was able to stay in the moment and do well. So it was fun to watch today.

“I like the way he carried himself. I like his overall demeanor and mound presence. I felt like he navigated a lineup that's tough to pitch to.”

Mathews, the Cardinals’ seventh-ranked prospect, per MLB Pipeline, averaged 94.3 mph on his four-seam fastball. Fastball velocity has always been a key for the left-hander. Mathews had his fastball humming in 2024, when he cruised through the Minor Leagues. That velocity dipped a little in 2025, when he battled a left shoulder injury.

Walks remained a small issue for Mathews, who averaged 5.09 BB/9 in 19 starts with Triple-A Memphis this season. Toronto didn’t chase much, even when Mathews got ahead in the count, so the lefty’s pitch count climbed early.

“Looking at the game, obviously frustrated, to be quite frank,” Mathews said. “That's two out of three walks [where] I started the counts 0-2 and then just got too fine with two strikes, which is kind of the story of my day.”

Mathews, like most pitchers, was hyper-critical of his performance but acknowledged it as an excellent building block. And looking past Saturday, his breakthrough represents the start of an exciting stretch for young Cardinals pitching.

Kyle Leahy, who pitched well again Friday, and Andre Pallante have emerged as consistent, controllable pieces in the rotation. Matthew Liberatore and Mathews bring more swing-and-miss upside. Add Michael McGreevy to the mix, and St. Louis suddenly has a promising collection of starting options for the years ahead.

“I think the easiest thing is you're all learning from one another,” Mathews said of joining a young Cardinals rotation.

For Marmol, Mathews’ debut was another step in figuring out which arms can become part of that long-term core.

“When you look at the season and trying to figure out what we have, what we don't have, and starting to build a core for what we want this to look like moving forward, man, he's a part of that future,” Marmol said. “And for him to get a taste of what it's like up here is awesome.”