The St. Louis Cardinals pitching staff might be in a constant state of volatility throughout all of 2026.

The Cardinals, amidst many other trades, dealt away starting pitching Sonny Gray this offseason and closer Ryan Helsley at the trade deadline last season.

St. Louis also netted several hurlers in return. President of baseball operations Chaim Bloom acquired starters Hunter Dobbins and Richard Fitts in respective trades, signed Dustin May to a one-year deal and acquired top 100 pitching prospect Jurrangelo Cijntje in a trade with the Seattle Mariners and Tampa Bay Rays.

Amidst all those moves and additions, it could be a converted reliever that takes the final spot in the starting rotation.

It's been expected this offseason that right-handed pitcher Kyle Leahy will make the full transition from the bullpen to the rotation this upcoming season and he made a decent case to earn the final starting rotation spot in '26.

Leahy took the mound for the first time in spring training in the Cardinals' 6-5 win against the Houston Astros on Sunday at CACTI Park of the Palm Beaches in West Palm Springs, Fla.

Leahy started the game and had a decent showing. He struck out three batters in two innings pitched, didn't issue a walk and allowed one earned run on one hit (one home run).

Leahy worked in his full arsenal: a four-seam fastball, a changeup, a slider, a sweeper, a two-seam fastball (sinker) and a curveball. He offered each pitch multiple times.

Leahy was one of St. Louis' most effective relievers last season. The former 17th-round MLB Draft pick posted a 3.07 ERA and fanned 80 batters in 88 innings pitched across a career-high 62 appearances (one start).

Leahy currently projects to be the fifth starter in the Cardinals rotation, according to FanGraphs. The four pitchers projected to be ahead of Leahy in the rotation are, in order: Matthew Liberatore, May, Andre Pallante and Michael McGreevy.

Pallante, McGreevy and Leahy are the only three pitchers projected to be in the rotation that have been drafted and developed by St. Louis. Leahy is the earliest draftee among the trio and is the only one of the three that was picked later than the fourth round.

It's unlikely St. Louis will be in contention for a playoff spot so early into its rebuilding process, and the team has no shortage of major league-ready starters (or fringe-major leaguers).

If Leahy continues to post solid numbers in his first season as a starter, there's a good chance he can be a more permanent fixture in the Cardinals' rotation going forward.

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