Cardinals Move Nolan Arenado to Diamondbacks: Full Details of the Trade

The St. Louis Cardinals are continuing to reshape their roster this offseason, parting ways with some veteran players. Following the trades of Sonny Gray and Willson Contreras to the Boston Red Sox, and with Brendan Donovan also garnering significant trade interest, the Cardinals have now made a major move involving one of their top stars, Nolan Arenado.

The Diamondbacks have secured the services of the star third baseman, a move that has huge implications for both teams. But what exactly are the Cardinals receiving in return for Arenado, whose massive contract and recent struggles made this trade inevitable?

What the Cardinals Receive: Jack Martinez and Significant Money Relief

In return for Arenado, the Cardinals will receive one key piece—pitching prospect Jack Martinez. The 22-year-old was the Diamondbacks’ eighth-round selection in the 2025 MLB Draft, and he represents the only player coming back to St. Louis in this deal.

Martinez is a pitching prospect who had a less-than-ideal 2025 season, posting a 5.47 ERA in 15 starts for Arizona State. Despite his struggles, Martinez still offers potential, and the Cardinals are hoping he can develop into a key arm for their future. However, the major value in this trade for St. Louis lies not in the prospect but in the financial relief they are receiving by taking on a significant portion of Arenado’s remaining contract.

Financial Details: Cardinals Take on $31 Million of Arenado’s Contract

The deal’s financial components are what make this trade particularly noteworthy. While Arenado is still owed $42 million over the next two seasons (2026 and 2027), the Cardinals have agreed to take on a hefty $31 million of that amount. This means the Diamondbacks will only be on the hook for $11 million of the $42 million owed to Arenado in the next two seasons.

The Cardinals’ decision to eat such a large portion of Arenado’s contract is tied directly to his struggles during the 2025 season. Arenado, once considered one of the best third basemen in the game, had a difficult year at the plate. He hit just .237 with a .666 OPS, marking the worst performance of his 13-year MLB career. This major regression in his production, particularly on the offensive side, undoubtedly impacted his trade value.

Arenado’s Remaining Contract: What the Diamondbacks Are Getting

Arenado is still a very capable defender at third base and brings significant experience to the Diamondbacks’ roster, but his offensive downturn is hard to ignore. With his contract for 2026 and 2027 at $27 million and $15 million, respectively, the Diamondbacks are now getting him at a relatively low cost for the next two years.

By taking on the remaining $31 million of Arenado’s deal, the Cardinals have essentially allowed the Diamondbacks to acquire the third baseman for a bargain price, considering his previous level of play. This gives the Diamondbacks a chance to see if Arenado can return to form offensively, while also strengthening their infield with one of the best defensive third basemen in the league.

The Cardinals’ Strategy: Shedding Salary and Future Development

For the Cardinals, this trade is part of a broader strategy to shed salary while focusing on rebuilding for the future. With Arenado’s regression in 2025, combined with his expensive contract, the Cardinals found themselves in a position where they needed to move him in order to free up financial flexibility. By taking on $31 million of Arenado’s contract, the Cardinals get some much-needed breathing room in their budget, which could allow them to make further moves as they continue to rebuild their team under a new front office philosophy.

The trade for Jack Martinez, while not a huge splash, provides the Cardinals with a prospect who could eventually contribute to the major league squad. Martinez still has work to do, but he represents the type of pitching talent that could develop over time, which fits the Cardinals’ long-term vision.

A Trade for Both Teams: Immediate Help for the Diamondbacks

This trade benefits both teams in different ways. For the Diamondbacks, adding Arenado is a significant move to bolster their lineup and improve their defense. Arenado has consistently been one of the top defensive third basemen in baseball, and even if his bat doesn’t fully bounce back, his glove alone could make him a valuable addition to a Diamondbacks team looking to compete in the National League.

Meanwhile, for the Cardinals, the trade is a necessary step toward moving forward in their rebuild. While they are losing one of their most iconic players, they gain financial flexibility and the chance to develop a promising pitching prospect in Martinez. This move signals that the Cardinals are looking to the future, and this trade is just the beginning of a broader plan to reshape their roster.

Conclusion: A Difficult But Necessary Trade for the Cardinals

The trade of Nolan Arenado marks the end of an era for the St. Louis Cardinals, as they part ways with one of the game’s most talented players. The return for Arenado—a single pitching prospect and significant financial relief—shows the impact of his disappointing 2025 season. While the trade may not have netted the Cardinals a top-tier prospect, it aligns with their broader goals of cutting costs and rebuilding for the future.

For the Diamondbacks, this is an opportunity to acquire an elite defensive third baseman who could provide immediate help. If Arenado can regain his offensive form, this trade could prove to be a steal for Arizona.

In the end, this trade serves as a reminder of how much the game of baseball can change in a short amount of time. Just a few years ago, Nolan Arenado was one of the game’s most sought-after players, but his recent struggles and massive contract have made him a more challenging trade piece. For the Cardinals, moving Arenado is a necessary step as they look to move forward, while for the Diamondbacks, it’s a calculated risk with the potential for a huge payoff.