On a brisk January day in 2026, the baseball world was rocked by a blockbuster trade: the St. Louis Cardinals sent veteran third baseman Nolan Arenado and a hefty sum of cash to the Arizona Diamondbacks in exchange for right-handed pitching prospect Jack Martinez. The move, confirmed by both clubs on Tuesday, signals a pivotal shift for two franchises at very different crossroads.
For Cardinals fans, the news comes with a mixture of nostalgia and inevitability. Arenado, a fixture at the hot corner since 2021, leaves St. Louis after five seasons marked by elite defense, clutch hitting, and a relentless drive that endeared him to the Gateway City faithful. "We are grateful for Nolan’s five years as a Cardinal, on and off the field—for his drive, his competitiveness, and for all of the memories he gave us," Cardinals president of baseball operations Chaim Bloom said in a statement. "As we continue to move forward, we are pleased to add another intriguing pitching prospect to our organization, and excited for the opportunity this move creates for a number of our players to step up and further establish themselves at the big league level."
The trade, however, is as much about finances and future planning as it is about on-field talent. Arenado, who will turn 35 in April, was owed $42 million over the next two seasons—$27 million in 2026 and $15 million in 2027—on a nine-year, $275 million contract originally inked with the Colorado Rockies. According to multiple reports, the Cardinals will cover $31 million of that amount, with the Diamondbacks responsible for just $11 million ($5 million in 2026 and $6 million in 2027). The Rockies, interestingly, are still on the hook for $5 million from an earlier deal, highlighting just how complex big-league finances can be.
Arenado’s departure closes a chapter for St. Louis, a club now firmly in rebuilding mode under Bloom. The Cardinals have already moved on from veterans Sonny Gray and Willson Contreras this offseason, and the Arenado deal is widely seen as both a salary dump and a chance to clear the way for top prospect JJ Wetherholt. With rumors swirling around second baseman Brendan Donovan and the likes of Masyn Winn and Nolan Gorman set to take on larger roles, the Cardinals are betting on youth and internal development as they look to retool for the future.
As for Arenado, his resume speaks for itself: 10 Gold Gloves, eight All-Star selections, five Silver Slugger Awards, and a career .282 batting average with 353 home runs over 13 seasons split between Colorado and St. Louis. Last year, however, was one of his toughest campaigns yet. Limited to 107 games by a right shoulder strain, Arenado posted a .237 average with 12 home runs and 52 RBIs—numbers well below his career norms. His slash line (.237/.289/.377) and .666 OPS were both career lows, and his power output has dipped in recent years, averaging just 18 homers per season over the last three years after being a perennial 35-40 home run threat in his prime.
Despite the downturn at the plate, Arenado’s defense remains elite. Even as he approaches his mid-30s, his glove work at third base is still among the best in the game, with above-average range and a knack for making the spectacular look routine. The Diamondbacks, who have been searching for a replacement at third since trading Eugenio Suarez to the Mariners at last year’s deadline, are banking on Arenado’s veteran presence and defensive prowess to anchor an infield that already features Geraldo Perdomo at shortstop and Ketel Marte at second base. Arizona had been linked to free agent Alex Bregman earlier in the offseason, but after Bregman signed a five-year, $175 million deal with the Chicago Cubs, the D-backs pivoted to Arenado as their top option.
Making the trade possible required Arenado to waive his no-trade clause—a right he had exercised just a year ago to block a move to the Houston Astros. This time, with St. Louis openly rebuilding and Arizona emerging as a contender in the National League, the fit was finally right. Arenado’s agent had previously indicated the third baseman would be open to moving positions to accommodate a trade "if it’s the right place to go," but for now, he’ll remain at third, potentially blocking prospects like Jordan Lawlar from immediate big-league time. The Diamondbacks’ decision to keep Marte at second and Perdomo at short solidifies their infield alignment heading into the 2026 campaign.
For Arizona, the deal is not without risk. Arenado’s offensive decline is notable, with his hard-hit rates and exit velocities among the lowest for MLB third basemen the past two years. But the D-backs are betting that a change of scenery, renewed health, and a playoff-caliber environment can spark a late-career resurgence. Even if his bat doesn’t fully rebound, his glove and leadership could prove invaluable for a young, ambitious club.
Heading to St. Louis is Jack Martinez, a 22-year-old right-hander drafted by Arizona in the eighth round of the 2025 MLB Draft out of Arizona State University. Martinez, who also pitched at Trinity University in Texas and Louisiana-Lafayette, posted a 6-4 record with a 5.94 ERA in 15 starts for the Sun Devils last season, striking out an impressive 110 batters over 77.1 innings. While his command remains a work in progress—he walked nearly 10% of batters faced—his fastball sits at 93-95 mph and can touch 97, complemented by a promising slider and changeup. Most scouts project Martinez as a potential back-end starter or bullpen arm, depending on how his control develops in the pros. He did not pitch in pro ball in 2025 and will make his professional debut in 2026 with the Cardinals.
The trade has wide-ranging implications for both teams. For the Cardinals, it’s a clear signal that the organization is prioritizing youth and payroll flexibility as it looks to the future. The move also opens up a path for Wetherholt, widely regarded as one of the game’s top prospects, to make his mark at the big-league level. For the Diamondbacks, the acquisition of Arenado is a bold statement of intent—a sign that Arizona is all-in on contending in the National League, even as questions remain about their bullpen and the long-term fit for some of their young infielders.
As the dust settles, both teams are left with new challenges and opportunities. The Cardinals, with a retooled roster and a focus on development, will see if their gamble on youth pays off. The Diamondbacks, meanwhile, hope that Arenado’s glove and experience can help push them over the top in a competitive NL West. One thing’s for sure: the 2026 MLB season just got a whole lot more interesting.
