Kyle Leahy's transformation shows what Cardinals new pitching development is capable of

Just a few months ago, it was hard to find Cardinals fans who supported the Kyle Leahy rotation experiment continuing on. Now? He's looked like one of the best starters in baseball for a significant stretch.

Since the All-Star Break, Leahy's owns the lowest ERA (1.70) of any starting pitcher in the National League. That trend dates all the way back to June 23rd, as Leahy also owns the lowest ERA in the National League over his last 11 starts (1.28).

Over that stretch of time, Leahy isn't just finding dumb luck; he's striking out more and more batters the deeper he gets into the season, and pairing that with allowing weaker contact. All of this amounts to Leahy rarely allowing damage on the mound and looking like a front-line starter for a while now.

By no means am I trying to sell you that Leahy is now a future ace, but man oh man, does this experiment look very, very good by the Cardinals now. Even with Leahy now running into his innings cap for the season, the future looks extremely bright for the Cardinals' right-hander, and his development has a significant impact on the future of the Cardinals' rotation and my confidence in the Cardinals continuing to develop more pitching talent.

The Cardinals success with Kyle Leahy is being mirrored with top prospects

Leahy was never some top prospect in the Cardinals system. Drafted in the 17th round back in 2018, Leahy bounced back and forth between starting and relief in the minor leagues before debuting as a reliever for the Cardinals back in 2023. They set him up for this transition back to the rotation by subtly building him up in the 2025 season, and in his first year starting, he owns a 3.13 ERA over 25 starts.

The Cardinals' patience with Leahy has been key to him eventually finding his success, but the Cardinals' new player development and performance staffs deserve a ton of credit for how they partner with their field staff to get the most out of players. Their success with Leahy now gives the Cardinals a very interesting starting option as they look ahead to the future, but it also should produce a ton of confidence in their ability to maximize their uber-talent prospects down below.

The prime example of this right now is Liam Doyle, whom the Cardinals selected fifth overall in the 2025 MLB Draft, and who now looks unhittable in Double-A after a rough beginning to his time there. The Cardinals not only started him in Double-A this year as an aggressive promotion, but they put him at a more difficult level and asked him to work on developing pitches other than his fastball, allowing him to go through struggles knowing that it would make him a much better starter on the other side.

Through Doyle's first 12 Double-A starts, he posted a 6.08 ERA, walking 12.8% of the batters he faced while striking out 29.8% of them. The stuff was there, but he was super inconsistent and would get beat up too often. Well, over his last nine starts, Doyle has a 1.60 ERA while striking out 32% of the batters he's faced, and he's consistently going five or more innings for Springfield during his appearances.

While third-party scouting outlets seem to be behind on this, Doyle is back to looking like one of the best pitching prospects in the game, and his hiccups early in the year will end up making him a much better Major League pitcher. And the excitement doesn't end there.

There are so many other arms in the system right now that should have Cardinals fans excited about the future. Tanner Franklin continues to look like one of the fastest-rising pitching prospects in the sport and should start finding himself on top-100 lists soon. Yhoiker Fajardo is killing it at Double-A and hasn't even turned 20 yet. Quinn Mathews has been showing flashes at the Major League level, and Cooper Hjerpe looks next in line to make his own debut.

Add in Brandon Clarke, Daniel Eagen, Jurrangelo Cijntje, Jacob Odle, Tegan Kuhns, Tekoah Roby, Mason Molina, or more, the Cardinals have a ton of arms who could make an impact sooner rather than later. Right now, the Cardinals seem to have hit their wall as a pitching staff and don't have options to turn to, but at this rate, once 2027 and especially 2028 roll around, they'll have dynamic arms to turn to.

Back to Leahy. As the Cardinals enter next season, he joins Michael McGreevy and Andre Pallante as three very stable and capable starters for their rotation. Quinn Mathews, Hunter Dobbins, and Richard Fitts should fit into that equation as well, and I'm sure the Cardinals are intrigued by what Hjerpe could do. Roby should be back from injury as well, and the Cardinals could even add another starter or two to their mix like they did with Dustin May this past offseason.

Leahy's rise gives the Cardinals the ability to shop a player like Pallante, who is a good starter but is nearing free agency and could bring back a nice trade return, as well as Matthew Liberatore, who looks destined for a change of scenery at this point. Long-term, it's probably best to still think of Leahy as a back-of-the-rotation starter, but if he translates this success into 2027, he could establish himself as more than that. And once guys like Doyle, Franklin, Fajardo, and others are ready to debut, the Cardinals will have a lot of pitching on their hands.

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