Nolan Arenado Trade Changes Diamondbacks' Infield Situation for 2026
The Diamondbacks acquired the veteran third baseman to stabilize their infield defense in 2026.
With the Diamondbacks committing to Ketel Marte for the foreseeable future, the offseason can finally start. General manager Mike Hazen has worked quickly to add experience to the lineup and bullpen this week.
The first major move was acquiring third baseman Nolan Arenado from the St. Louis Cardinals. The deal allows Arenado to spend the next two years in Arizona, where he lives in the offseason. He’s spent at least a decade on the other side of Salt River Fields, from his time with the Colorado Rockies.
The Diamondbacks didn’t pay much to land Arenado. They gave up a lottery ticket prospect in Jack Martinez and are only responsible for $11 million over the next two years. That is likely due to Arenado’s full no-trade clause, plus 10-and-5 rights, which negated any potential leverage the Cardinals might have had otherwise.
Diamondbacks Infield Situation Following Nolan Arenado Trade
Arenado is coming off the worst season of his career. He slashed just .237/.289/.377 with 12 home runs and an 84 wRC+ in 107 games. The 34-year-old has seen his power significantly decline over the past three seasons despite solid contact rates. Hazen mentioned stabilizing the infield defense as a key priority this offseason.
While he’s no longer the elite defender and MVP candidate he was five years ago, he still provides value to the Diamondbacks. He is still a good defender at third base (+6 DRS/+3 OAA) and adds a leadership element to the clubhouse that was lacking in 2025.
Hazen seems to be banking on a rejuvenation for the future Hall of Famer, now that he’s gone from a rebuilding club in St. Louis to one that hopes to contend in Arizona. He’s probably not a 140-start guy at third base at this stage of his career due to his poor numbers vs. right-handed pitching. Arenado still hit lefties decently enough, with a .294/.339/.402 (102 wRC+) in 2025.
Here’s the Diamondbacks' likely starting infield:
First Base: Pavin Smith/RHH platoon
Second Base: Ketel Marte
Shortstop: Geraldo Perdomo
Third Base: Nolan Arenado
Veteran infielder Ildemaro Vargas is a candidate for a bench role, especially as a complement to Arenado at third. Arenado is likely starting 110-120 games, with some games at DH mixed in. Hazen pushed back a little on the idea of Marte getting more reps there. Against lefties, it could be a mix-and-match situation with Marte, Arenado, and Gabriel Moreno there to keep their bats in the lineup.
Jordan Lawlar and Blaze Alexander’s Future with the Diamondbacks
Assuming Arenado is the primary starter at third base, that leaves questions for the fate of both Blaze Alexander and Jordan Lawlar. Alexander is out of options entering the 2026 season, while Lawlar has just one remaining.
Both infielders had previous opportunities to carve out a role. Given the current state of the roster, no bigger opportunity exists than the one in front of them. While Arizona’s is strong 1-4, they need at least one of the two to step up to lengthen the lineup. That, in turn, should allow them to be more productive offensively as a team and grind down the opposing starter quicker.
Hazen clearly indicated that both young infielders will get reps in the outfield. Alexander played some games in both left and center field at the tail-end of the 2025 season. It’s unclear how his shortstop defense looks after a disastrous run there in 2024, but he could be a super utility option if it’s improved. He’s also a candidate to play third when Arenado needs a day off or is starting at DH.
With a thin outfield, especially following the Jake McCarthy trade, there should be more opportunities for both young infielders to play more regularly. While Lawlar’s option gives the Diamondbacks some flexibility, the former top prospect has nothing left to prove in Reno.
The Diamondbacks have a completely open spot in left field. Alexander is tentatively projected as the starter according to Roster Resource. With Alek Thomas relegated to mostly a platoon role, both infielders will play against left-handed pitchers. The only question is who plays center field.
Arenado Forms Bridge to D-backs Top Prospect at Third Base
Arenado is under contract for two more seasons, which forms a successful bridge to top prospect LuJames Groover III. Groover moved around the infield in his first year in the organization, but played exclusively at third base with Amarillo in 2025.
The 2025 Southern League batting champion is ticketed for Triple-A Reno to start the 2026 season. His ETA could be tied to Arenado’s health, depending on the severity. Alexander, Lawlar, or Vargas could fill in for a short-term absence; a long-term one could lead to Groover’s 40-man clock starting.
Groover will be on Arizona’s 40-man roster no later than November. It’s unlikely the organization leaves him unprotected, although they have a lot of decisions ahead with their prospects.
Groover has one of the best hit tools in the Diamondbacks organization. From his time in the Arizona Fall League, I noticed his ability to spray the ball from line-to-line with authority. However, the power has been slow to develop. Most of his contact in the AFL was low-liners, with launch angles in the 8-19° range. Making more contact in the 20-30° range should help improve his home run power.
Other than Groover, the Diamondbacks don’t have many prospects at third base. Jansel Luis got some run there in the Arizona Fall League in 2025 after playing primarily second base. Yassel Soler and Enyervert Perez both project as 1B/DH types.
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Michael McDermott is the founder and publisher of D-backs Under Review. He’s covered the Arizona Diamondbacks and their farm system for multiple publications since 2015. Michael has covered 50 MLB games as credentialed media at Chase Field and four seasons of the Arizona Fall League.