It’s been years since the Cardinals had a starting pitching prospect arrive with as much anticipation as left-hander Quinn Mathews, who will make his Major League debut on Saturday against the Blue Jays at Rogers Centre.
Ever since the Cards’ No. 7 prospect per MLB Pipeline tore through the Minor Leagues in 2024, many have been eager to see him toe the rubber for St. Louis. His path took a bit longer than many expected, but after overcoming an uneven 2025 season and command issues early this year, Mathews has done all you can ask for to earn his shot.
In 19 starts for Triple-A Memphis this season, the 25-year-old has posted a 3.13 ERA while striking out 111 batters in 92 innings of work. He hit a whole new level on the mound as the season progressed, recording a 1.59 ERA over his final 10 starts while completing at least six innings in each of his last four outings.
Mathews’ final Triple-A outing on July 24 was one of his best. He allowed three hits and three walks while striking out 10 over seven scoreless innings, putting an exclamation point on his case for a promotion.
For an organization that has made it a priority to rebuild its pitching pipeline after years of struggling to produce homegrown starters, Mathews' debut feels significant. He represents the first wave of intriguing arms who the Cardinals hope will impact the Major League club soon.
During Mathews’ first professional season in ‘24, he was named the Minor League Pitching Prospect of the Year after posting a 2.76 ERA in 143 1/3 innings while striking out 202 batters. In doing so, he became only the second Minor League pitcher to surpass 200 strikeouts since 2011. Mathews had the baseball world on notice, leading MLB Pipeline to rank him as the 45th-best prospect entering 2025.
COMPLETE CARDINALS PROSPECT COVERAGE
Then, his rise stalled. Mathews battled early shoulder trouble, lost some fastball velocity and struggled with his mechanics, leading to a 3.93 ERA in 94 innings. The command issues continued early this season, but as that began to stabilize, his ability to miss bats and limit damage allowed Mathews to excel against Triple-A hitters.
While Mathews’ command could still use more refining, his strikeout stuff is something the Cardinals haven’t seen from one of their young starters in quite some time. He doesn’t feature prominently on national prospect lists anymore, but Mathews is back to pitching with the kind of authority that had him as one of the more exciting arms in Minor League baseball just a few years ago.
The last St. Louis pitching prospect to debut with this kind of pedigree was Matthew Liberatore in 2022. The Cardinals had acquired Liberatore in the Randy Arozarena trade and he checked in as Pipeline’s No. 43 prospect prior to his debut. In recent years, pitchers like Michael McGreevy, Andre Pallante and now Kyle Leahy have impressed in their first cracks as big league starters. But Mathews feels like the first of a new wave of pitchers coming to St. Louis, one that comes with a different mold.
Mathews, like many of the starters coming through the Cardinals’ system right now, is at his best when he is getting opposing hitters to swing-and-miss. He gets excellent whiff rates on his slider and changeup, and his fastball has enough juice to get past opposing hitters as well. While the Cards’ rotation has relied heavily on ground balls and soft contact, Mathews has that swing-and-miss capability they have been searching for.
Mathews is a window into the future for Cardinals fans. And by allowing him to get his feet wet in St. Louis now, he’s also giving the coaching staff and front office a chance to map out its rotation plans moving forward. With a number of young arms already at the Major League level and more starters knocking on the door, the Cards are going to want to see how Mathews fits into that equation.
St. Louis has been sliding in the standings, and Mathews' debut won’t solve everything. But perhaps he can give the club the kind of jolt that helps it put up a fight in the National League Wild Card race down the stretch.
That first look comes Saturday.