Desert Oasis: Zac Gallen Returns to Diamondbacks on One-Year Deal

After a long, quiet offseason, Zac Gallen is back where he started. In November, he turned down a qualifying offer, a one-year deal from the Diamondbacks worth $22.025 million. On Friday, Gallen and the Diamondbacks agreed to terms on a new contract. Stop me if you’ve heard this one before – it’s for one year and $22.025 million (with deferrals that drop the net present value to $18.75 million). Arizona’s ace is once again at the top of the rotation in the desert.

Gallen was my no. 19 free agent this winter, and I’ll just reproduce the first line of my write-up here: “After looking at Gallen’s résumé for about an hour, I came to an obvious conclusion: I’m glad I’m not a major league GM.” He had a severe case of pumpkinization in 2025. He missed fewer bats, drew fewer chases, walked more batters and struck out fewer, gave up louder contact, didn’t keep the ball on the ground, and lost a bit of velocity. It was the worst season of his career by a large margin; his 4.83 ERA might have been a caricature of his performance, but all of his advanced run prevention estimators surged to career-worst marks, too.

As a platform year, it left something to be desired. But I still think Gallen was right to turn down his QO and survey the landscape. After that didn’t work out, however, he made the obvious choice: Run it back in the same place and try again. Given that he put up a 3.20 ERA (3.22 FIP, 3.47 xFIP) from 2022 through 2024, worth a whopping 12.2 WAR (14.9 rWAR), betting on at least a little bit of bounce-back before a second trip to free agency surely felt very appealing.

I don’t have a strong feel for what Gallen’s 2026 will look like. The range of outcomes is enormous. Did you just see what I said about his last four seasons? I do think that there’s a decent chance of a rebound to his prior form, a borderline ace who you’d be ecstatic with as a no. 2. His approach has never been simple to figure out; even at his best, he threw a boatload of pitches that our models weren’t enamored with and made things work with command and deception. Now, after that skill basically turned off for a year, I’m worried that he can’t turn it back on again – but my base case is still that he figures it out. It’s the kind of risk I’d be interested in taking as a borderline playoff team.

That describes the Diamondbacks perfectly. After a stirring World Series run in 2023, they haven’t returned to October despite averaging 84.5 wins in the past two years. The time to strike is now. Ketel Marte, their offensive pacesetter, is in the tail end of his prime. Corbin Carroll, Geraldo Perdomo, and Gabriel Moreno are each under contract for a while, and they’re all great right this minute. Wasting a year of this lineup without sufficient pitching would be a tragedy.

To be fair, it’s not like this team hasn’t tried. The D-backs signed Corbin Burnes, the top free agent pitcher, last year, only for him to need elbow surgery. The year before that, they signed Eduardo Rodriguez to a four-year deal worth $80 million, and there was also the whole Jordan Montgomery saga. Earlier this winter, they gave Merrill Kelly two years and $40 million to return to the fold.

Even with all of those signings, though, Arizona needed more. Before adding Gallen, the Diamondbacks were depending on Michael Soroka, who has combined for 201 major league innings over the past five years, as an everyday member of their rotation. Ryne Nelson, another key contributor, faded down the stretch and has never managed 30 starts in his three years in the rotation. Brandon Pfaadt has hit that 30-start plateau in two straight years, but he has a 4.97 ERA in that stretch, so his leash is not infinite. Their farm system has a few possible candidates in the upper minors, but without Gallen, they might have needed multiple of those guys to pan out at the major league level. Even after plugging Gallen into the projections, we have this as a below-average rotation. It’s not so much that the D-backs don’t have five capable major league starters. The problem is that teams need more than that, and also need some upside, because a bunch of league-average starters is usually not enough to make a playoff rotation.

Our playoff odds give Arizona a 32% chance of making the playoffs, with an 81.4-win median projection. That’s the exact right place in the win curve where adding talent pays off most, and this team has mostly done that so far this winter. It brought back Kelly (traded at the deadline) and Gallen, traded for Nolan Arenado, and signed a smattering of interesting bargain free agents for depth. Gallen might only add a win or so to this projection, since he’s replacing pitchers who are better than replacement level, but the Diamondbacks are in a situation where every win matters. They missed the playoffs on a tiebreaker in 2024, and by a mere three games in ’25. Forget a calculation of dollars per win; they are thinking about dollars per marginal increase in playoff odds, and from that perspective, adding Gallen is a no-brainer.

I think it’s reasonable to wonder whether Arizona missed out on a chance to add a top first baseman or DH earlier in the winter. Pete Alonso and Kyle Schwarber might have been out of the team’s price range, but either of the NPB hitting stars — Munetaka Murakami or Kazuma Okamoto — would have been interesting fits in Phoenix. Some of the top starting pitchers would’ve looked mighty nice there, too. But for whatever reason, the Diamondbacks didn’t land any of them, and here we are in mid-February. It’s like that old saying about saving for retirement: The best time to sign a difference-making free agent was two months ago. The second-best time to sign a difference-making free agent is now.

It takes two to sign a contract, but in this case, Gallen’s incentives are lined up with Arizona’s. He wants to hit free agency again without a qualifying offer attached, and preferably with a good platform year on his résumé. The squad would like nothing more than for that to happen; the possible futures where Gallen has a resurgent year include a lot of playoff appearances. That’s a good capper on the signing, in fact. You know what Gallen is capable of doing in Arizona, and both he and the Diamondbacks are hoping that he shows it one more time in 2026.