If you’ve been focusing only on Arizona Diamondbacks GM Mike Hazen’s major league signings this offseason, you might be underwhelmed by the limited free-agent pitching acquisitions beyond Merrill Kelly and Taylor Clarke. However, Hazen has been quite active at the minor league level, signing several pitchers who could potentially make an impact on an MLB roster by 2026. This article highlights those key additions and evaluates their chances of breaking through.
The Five Most Promising Minor League Pitchers
Hazen has signed five minor league pitchers who stand the best chance of contributing at the major league level in 2026 — assuming they maintain good health.
Jonathan Loaisiga (RHP):
A detailed article by Makakilo provides great insights on Loaisiga, who arguably has the highest ceiling of this group to add value in the majors in 2026.
Derek Law (RHP):
Law proved to be an effective reliever between 2019 and 2024, posting solid ERAs, including a 3.60 with the Reds in 2023 and 2.60 with the Nationals in 2024. However, he will miss the entire 2025 season due to a forearm injury and has not pitched since 2024, raising concerns about his future health and effectiveness.
Thomas Hatch (RHP):
In 2023, Hatch showed moderate success as a reliever in MLB before heading to Japan’s Hiroshima Carp, where his stats were less favorable despite underlying metrics suggesting he wasn’t as ineffective as they seemed. After returning to the U.S., he spent most of 2024 in Triple-A with the Royals and had mixed results in limited MLB innings. He was later claimed by the Twins and appeared in 11 games but posted elevated ERA and advanced metric numbers, indicating struggles.
Sean Dubin (RHP):
Dubin’s best season came in 2024, pitching 45.1 innings for Houston with a 4.17 ERA and solid peripherals. His 2025 performance declined slightly, leading to a waiver claim by Baltimore, where he pitched in seven games, showing some promise. This signing might be one of Hazen’s underrated offseason moves if Dubin returns to form in 2026.
Isaiah Campbell (RHP):
Campbell had a strong debut with Seattle, posting a 2.83 ERA in 2023, though some advanced stats suggested room for improvement. Injuries limited his 2024 season, resulting in poor MLB numbers, but he showed increased velocity in 2025 during a mostly Triple-A season. If he builds on that progress, Campbell could become a valuable MLB arm.
Other Prospects and Rule 5 Draft Picks
Several other pitchers have yet to debut in MLB, with varying levels of minor league experience. Pitchers such as Gerardo Carrillo, Indigo Diaz, and Junior Fernandez remain unproven at higher levels, making their major league contributions in the near future unlikely.
Regarding Rule 5 Draft acquisitions, the Diamondbacks did not select players in the MLB phase but added three in the Triple-A phase, including two pitchers:
Sean Hurney (RHP):
Hurney, who played only at Double-A last year with a 4.24 ERA, has had multiple organizational moves and faces a daunting challenge adjusting to the hitter-friendly Pacific Coast League. His odds of succeeding enough to reach the majors seem slim.
Antonio Menendez (RHP):
Menendez put up strong numbers in Double-A during 2024 and 2025 despite some indications of luck influencing his results. His initial Triple-A stint was tough, but he could rebound in 2026, enhancing his chance of an MLB debut.
Fan Take:
These minor league signings reveal a strategic long-term approach by GM Mike Hazen, emphasizing depth and development rather than immediate marquee additions. For baseball fans, this focus on nurturing young arms could lead to sustainable success and exciting talent breakthroughs in the coming years, highlighting the importance of farm system strength in today’s game.
