After more than a year of speculation and more twists and turns than a roller coaster, the other shoe has finally dropped: The St. Louis Cardinals have reportedly agreed on a trade involving third baseman Nolan Arenado, sending him to the Arizona Diamondbacks in exchange for right-handed pitching prospect Jack Martinez. According to Nick Piecoro of The Arizona Republic, St. Louis is also sending along $31 million to help pay off the $42 million remaining on Arenado's contract, leaving the D-backs will be on the hook for just $11 million total over the next two seasons.
Just as crucially, Arenado has agreed to waive his no-trade clause and accept the deal, meaning we won't have any more last-minute changes of heart. Moving Arenado's contract was the biggest remaining obstacle in front of Chaim Bloom as he looked to reset the Cardinals' aging and expensive roster, and now that obstacle is behind him — a surprising and a little anti-climactic end to one of the weirdest sagas in baseball.
Cardinals-Diamondbacks Nolan Arenado trade details and reasoning
The Cardinals have been trying to move on from Arenado for a long time now; they in fact had a deal in place to send him to the Houston Astros last winter, only for the third baseman to about-face and exercise his no-trade clause. But after another disappointing season for St. Louis, not even Arenado could deny that this marriage had run its course — and it's hard to justify paying $30 million-plus to a middling player when you're winning 75-80 games a year. Arenado was hardly a flop in a Cardinals uniform, earning an All-Star nod in each of his first three years with the team, but it was time to start over.
We didn't quite expect Arizona to be the team to offer St. Louis an escape hatch, although in hindsight maybe we should. The D-backs are too talented to tear things down but don't have a ton of resources with which to upgrade what was an 80-win roster in 2025. The team could never find a reliable answer at third base last season, and Arenado will at least provide that much without muddying the long-term picture much at all.
Cardinals trade grade: B-
It's easy to look at this deal, in which St. Louis pays down a full three-quarters of Arenado's remaining salary without getting all that much in return, and wonder what might have been. You can certainly second-guess how John Mozeliak handled this situation, even while acknowledging that Arenado left the team up a creek without a paddle when he nixed the Astros trade. Whatever the Cardinals were poised to get from Houston, it was likely better (and less expensive) than this.
Still, given the hand he was dealt, I think Bloom did alright here. The market for Arenado was essentially non-existent: His bat appears to have all but evaporated (.666 OPS last season), and as his defense declines in his mid-30s, he's just not much more than an average player at this point — and even "average" might be a generous descriptor. St. Louis will still be on the hook for a good chunk of money, but they don't figure to be spending big over the next couple years of this rebuild anyway, and the $11 million Arizona is taking on makes a difference.
An eighth-round pick in the 2025 MLB Draft, Martinez is a 22-year-old who posted a 5.47 ERA at Arizona State last season. But he posted impressive strikeout rates (12.8 K/9 in 2025), and with a big fastball and a couple of workable offspeed offerings, he does have some tools to dream on. With the right development, he could at least develop into a big-league reliever, and again, getting anything of potential future value for Arenado at this point should be considered a win. It's not a home run, but it's making the best of a bad situation.
Diamondbacks trade grade: C
I understand the idea here, in theory. Arizona isn't looking to tear things down, not with Ketel Marte, Corbin Carroll and Geraldo Perdomo in the lineup and Corbin Burnes entering the second year of a $210 million contract. But if they want any shot at contention in 2026, they have some real upgrading to do — like, for example, at third base, where former top prospect Jordan Lawlar struggled so mightily he got bumped to DH and Blaze Alexander profiles more as a useful bench piece than an everyday starter.
If nothing else, Arenado brings stability: He'll take the field every day, play solid defense and bring veteran leadership to what is still a pretty young clubhouse. It's hard to substantially identify a better alternative, given the paucity of options in free agency (Bo Bichette and Alex Bregman were not in Arizona's price range, not without moving on from Marte) and the trade market.
But still, I have to ask: to what end? Sure, Arenado is a better fit at third base than anyone currently on the roster, but what are you really getting by bringing him in? He's not moving the needle for you, and at this point there appears to be only downside risk — risk that his defense continues to deteriorate with age, leaving him with very little to fall back on. The D-backs aren't giving up a ton here, so it's tough to get on them too much. Then again, Martinez might be a useful prospect to a team with precious little pitching depth as is, and $11 million in payroll certainly isn't nothing. Given how little interest there was for him around the league, is this the price Mike Hazen had to pay?