Diamondbacks Eye Lucas Giolito as Zac Gallen Declines Qualifying Offer

The Arizona Diamondbacks face a pivotal offseason after Zac Gallen declined his qualifying offer, leaving a significant void in a pitching staff already lacking depth. With Gallen’s future uncertain, the team appears ready to pursue other options in free agency, including right-hander Lucas Giolito. The Diamondbacks hope to stabilize their rotation and remain competitive in the National League West.

Giolito, who returned from significant elbow surgery and made 26 starts for the Boston Red Sox in 2025, posted a solid 3.41 ERA with 121 strikeouts over 145 innings. His performance has attracted interest from multiple teams, and Arizona has reportedly engaged in early talks with the 31-year-old veteran. For the Diamondbacks, adding Giolito could help offset the loss of Gallen and other rotation departures.

Arizona’s starting rotation faces additional challenges. Merrill Kelly was traded at the 2025 trade deadline, and Corbin Burnes is expected to miss a significant portion of the 2026 season while recovering from Tommy John surgery. These absences put extra pressure on the front office to secure quality innings from experienced arms like Giolito.

While Giolito represents a potential solution, the Diamondbacks will likely face competition from other clubs seeking to strengthen their pitching staff. How Arizona navigates these free-agent discussions could define the team’s trajectory for the upcoming season.

1. Giolito’s Bounce-Back Season

Lucas Giolito returned to the mound in 2025 after missing the entire 2024 season due to a torn UCL. His performance in Boston demonstrated both resilience and effectiveness, finishing with a 3.41 ERA, 0.1290 WHIP, and 121 strikeouts in 145 innings. Before the injury, Giolito had already established himself as a durable, high-strikeout starter capable of handling a full workload. His 2025 campaign reinforced his value, showing that he could still be a frontline starter in a competitive rotation. The Diamondbacks view Giolito’s experience and pitching style as a key fit for their needs, particularly with younger arms on the roster who could benefit from a steady veteran presence. If Arizona successfully signs Giolito, he could serve as a cornerstone while the team evaluates the status of other free agents and potential trades, helping to provide stability in a rotation otherwise facing uncertainty.

2. Pitching Depth Concerns for Arizona

Beyond Gallen and Giolito, the Diamondbacks have several holes to fill in their rotation. Trading Merrill Kelly and Burnes’ extended absence leave Arizona with limited options to anchor the starting staff. The organization will need to balance free-agent signings with potential internal options, considering both immediate performance and long-term development. The team’s ability to add experienced starters could also impact its competitiveness in the National League West. Front office discussions are likely focused on securing at least one veteran arm while leaving flexibility for additional acquisitions. Arizona’s strategy will hinge on landing Giolito, pursuing Gallen, or potentially exploring both options if financial and contractual terms align. With the offseason just beginning, the Diamondbacks’ rotation decisions will be crucial in shaping the 2026 roster and establishing pitching stability for the future.

3. Competition and Outlook

Giolito’s free-agent market is expected to be competitive, with several teams interested in adding a proven starter. The Diamondbacks’ early engagement signals intent, but securing him will require navigating interest from other suitors. Zac Gallen’s free agency adds another layer of complexity. Ideally, Arizona could retain Gallen while signing Giolito, but both moves will likely come with financial and strategic challenges. How Arizona approaches this offseason will have implications not just for 2026 but for long-term roster construction, particularly as they attempt to complement a growing core of position players. Securing a veteran starter like Giolito could provide stability and leadership, helping the Diamondbacks remain competitive while addressing significant rotation concerns.