D-backs pitching coach Brian Kaplan will not return for 2027 season

What happened

Arizona's pitching coach Brian Kaplan will not return for the 2027 season after two years in the role, MLB.com's Steve Gilbert reported. The Diamondbacks are parting ways with Kaplan as his two-year tenure concludes, leaving one of the more consequential staff positions in the organization open heading into what figures to be a busy offseason in the desert.

Why it matters

A pitching coach's fingerprints are on everything — pitch mix decisions, mechanical adjustments, the quiet conversations in the bullpen that never make a box score. The departure means Arizona will be introducing a new voice to a pitching staff that finished a season with real complexity: some arms outperformed their underlying metrics by a meaningful margin, others did not, and the front office now gets to decide what kind of developmental philosophy it wants shaping the next chapter.

The timing is notable. The Diamondbacks enter this offseason with a clear offensive agenda — GM Hazen confirmed, per prior Posterior Wire reporting, that the club will prioritize adding left-handed bats at first base and designated hitter after struggling against right-handed pitching in 2026. That offensive retooling will demand a pitching staff capable of holding leads and competing in a division that does not offer many soft landings. Whoever steps into Kaplan's role will be asked to hit the ground running.

There is also the broader organizational picture to consider. The uncertainty surrounding Ketel Marte's future with Arizona — flagged by D-backs executives in prior reporting, with a trade described as possible despite Marte's full no-trade rights — means the roster Kaplan's successor inherits could look meaningfully different from the one Kaplan managed. A new pitching coach arriving alongside potential roster turnover is a different assignment than a continuity hire walking into a stable environment. The two situations are not directly connected in the available reporting, but they are unfolding in the same offseason, and the new coach will navigate whatever the front office ultimately builds.

The numbers

Eduardo Rodriguez's 2026 season offers a useful lens on what Kaplan's staff was working with — and what made it complicated to evaluate. Rodriguez posted a 2.89 ERA for Arizona in 2026, a figure that sat well below what ERA estimators projected at approximately 4.4. Per prior Posterior Wire reporting, that gap was driven by elite pitch location, reflected in a 109 Location+ mark, rather than by underlying stuff metrics. In other words, Rodriguez's success was real, but it was built on a foundation that estimators tend to discount.

That kind of outcome — a pitcher outperforming his peripherals through location and command rather than raw velocity or movement — is exactly the sort of result that invites questions about the environment a coaching staff creates. Whether that approach translated broadly across the staff is not addressed in the available reporting, but it is the kind of data point that will be part of any honest evaluation of the tenure. The front office will be weighing it as the search for Kaplan's successor gets underway.

Where the club stands

Arizona finished 86-76 (.531), landing third in the NL West, 14 games back in the division race. The club entered the offseason having been eliminated from both the division race and the Wild Card race, closing the year on a two-game losing streak and sitting fourth in Wild Card positioning, 2.0 games relative to the cut line.

An 86-win season is not a disaster, but it is not a destination either — it is the kind of record that demands honest self-assessment. The Diamondbacks are close enough to contention to believe in the core, far enough from the postseason to know that something needs to change. The pitching staff is now one of the levers the front office can pull, and the coaching vacancy is the first formal expression of that.

The division context matters here too. Third place in the NL West, 14 games back, is a gap that does not close through incremental adjustments alone. The front office has already signaled its offensive intentions. The pitching side of the ledger now has a vacancy at the top, and the two searches — for bats and for a pitching coach — will be running in parallel through the fall.

What we don't know yet

The obvious open question: who steps into the role? No candidate has been reported, and the search process has not been described in the available reporting from Steve Gilbert or elsewhere. It is also unclear whether Arizona will look internally — promoting from within the organization's system — or pursue an external hire with major-league experience elsewhere. Both paths are common in these situations; neither has been indicated here.

It is also worth noting that the Marte situation remains unresolved. How aggressively the front office moves on the offensive additions Hazen described, and how the roster ultimately takes shape, will define the context the new pitching coach walks into. A hire made this fall may be coaching a meaningfully different group of pitchers by the time spring training opens.

What to watch

The pitching coach search is the immediate item on the agenda, and the timeline carries practical weight. Clubs that move quickly on staff hires give their new coaches more runway to build relationships with pitchers before spring training — a consideration that tends to accelerate these searches even when the front office is juggling other priorities, and Arizona's front office is clearly juggling other priorities.

Watch also for how the club's offseason transactions interact with the pitching staff picture. If the club adds left-handed bats as Hazen indicated, the lineup construction changes, which in turn shapes how the pitching staff is deployed and what kind of arms the new coach will be developing. The Marte situation, still unresolved, adds another variable to an already layered offseason.

The Rodriguez situation — a pitcher who outperformed his estimators by a wide margin on the strength of elite location — is also worth tracking as a data point in the coaching search. Whether Arizona prioritizes a coach with a similar command-first developmental philosophy, or moves in a different direction, will become clearer once a hire is made. For now, the seat is empty, the offseason is open, and the desert has questions.