Predicting Cardinals’ next big trade before deadline

The 2025 Cardinals season began with uncertainty. The team was coming off back-to-back disappointing years, and the front office had signaled a “reset,” focusing on player development and payroll flexibility. However, a string of early-season victories and a remarkable nine-game winning streak in June changed the calculus. Suddenly, St. Louis found itself just one game out of the final Wild Card spot, with playoff odds that have steadily improved since Opening Day.

This resurgence has not gone unnoticed. Club president John Mozeliak has publicly stated that if the team remains in contention, ownership is prepared to support deadline acquisitions that could bolster the roster for a postseason run. The Cardinals’ fanbase, long accustomed to competitive baseball, is energized once again, and the front office recognizes the importance of seizing this opportunity.

Despite their improved play, the Cardinals have clear areas that need reinforcement. The rotation, while serviceable, lacks a true No. 2 starter behind Sonny Gray. Injuries and inconsistency have plagued the back end, and there is a consensus that adding a reliable, playoff-tested arm could be the difference between a one-and-done Wild Card appearance and a legitimate October run. Additionally, the bullpen could use another high-leverage reliever, especially with Ryan Helsley and Phil Maton both set to hit free agency after the season.

Offensively, the lineup has been streaky, but the front office’s primary focus remains on pitching. The Cardinals’ deep farm system gives them the flexibility to pursue a significant upgrade without mortgaging their future

The Predicted Trade

After surveying the market and the needs of contending teams, the most likely blockbuster trade before the deadline is the Cardinals acquiring starting pitcher Merrill Kelly from the Arizona Diamondbacks. Kelly, a proven postseason performer with a team-friendly contract through 2026, is precisely the type of arm St. Louis covets. The Diamondbacks, hovering on the edge of contention but facing a roster crunch and a need to retool for the future, are open to moving Kelly for the right package of prospects[9].

Projected Trade Proposal

Cardinals receive:

• Merrill Kelly

Diamondbacks receive:

• Quinn Mathews
• Thomas Saggese
• Chase Davis

This package represents a significant but calculated investment by St. Louis. Mathews, the Cardinals’ No. 2 prospect and reigning Minor League Pitching Prospect of the Year, headlines the deal. Saggese, a versatile infielder with a strong hit tool, and Davis, a power-hitting outfielder with upside, round out the offer. For Arizona, the return jumpstarts a retool with three near-MLB-ready talents, while St. Louis lands a workhorse starter to anchor their playoff rotation[7][8][10].

Why This Trade Makes Sense

For the Cardinals, acquiring Kelly is about capitalizing on momentum and addressing their most glaring weakness. Kelly’s postseason experience, durability, and ability to pitch deep into games provide immediate stability. He slots in behind Gray, giving the Cardinals a formidable one-two punch for a potential playoff series. With the offense showing signs of life and the bullpen holding its own, bolstering the rotation could be the final piece of the puzzle.

The willingness to part with top prospects like Mathews and Saggese underscores the front office’s belief that the current roster can compete now. The Cardinals’ farm system remains deep, with players like Tink Hence, JJ Wetherholt, and Jimmy Crooks still in the pipeline, ensuring that the future is not mortgaged for the present[7][11].

For the Diamondbacks, this trade is about maximizing value for an asset that may not fit their long-term plans. By acquiring three high-upside prospects, Arizona positions itself for a quick turnaround, while also clearing payroll flexibility for future moves.

This deal would send shockwaves across the National League. The Cardinals, long known for their measured approach, would be making a bold statement: the time to win is now. For a fanbase hungry for postseason success, the acquisition of Kelly would signal a renewed commitment to contending and could reenergize attendance and excitement at Busch Stadium.

As the 2025 trade deadline nears, the Cardinals are poised to be one of the most fascinating teams to watch. By targeting Merrill Kelly and leveraging their prospect depth, St. Louis is making a calculated gamble that could pay off in October. If completed, this trade will not only define the Cardinals’ deadline but could also set the stage for a deep playoff run and a new era of success in St. Louis