Arizona’s bullpen struggles are a focal point, amplified by injuries to AJ Puk and Justin Martinez as the club eyes a postseason return. Archie Bradley’s 2017 peak (3.5 bWAR, 1.73 ERA, 1.04 WHIP) stands as the blueprint for a high-leverage reliever, while Byung-Hyun Kim’s 2002 breakout and Corey Knebel’s 2017 form illustrate the volatility and peak upside of late-inning arms. Hazen’s group faces questions about coaching and talent acquisition to stabilize the bullpen and sustain a playoff push.

Arizona Diamondbacks RHP Shelby Miller has emerged as a surprising closer in the wake of injuries to Justin Martinez and A.J. Puk. After a shaky ninth inning outing for Martinez, Miller stepped up and earned his fourth career save, showcasing a strong fastball velocity that has helped him maintain a solid strikeout rate of 29.8%. Despite concerns about his history of inconsistency, he may be the best bet for saves in Arizona's bullpen.

Emilio Pagan of the Cincinnati Reds is solidifying his role as the primary closer, particularly with Alexis Diaz struggling with command and now in Triple-A. Pagan's performance has improved his visibility in fantasy leagues for those in search of saves, despite being prone to giving up home runs. Additionally, Luke Weaver has emerged as a potential saves option with Devin Williams underperforming recently.

The Miami Marlins have made a key move ahead of the 2024 trade deadline, sending A.J. Puk to the Arizona Diamondbacks in exchange for infield prospect Deyvison de los Santos. Puk, who was once a top prospect with the Oakland Athletics, has transitioned to a reliable middle reliever since his debut in 2019. He has excelled this season with a 1.32 ERA and two saves for the Diamondbacks, though he is currently sidelined due to a flexor strain in his elbow. Despite the injury, the team remains optimistic about his recovery, believing he won't need surgery. In the meantime, Justin Martinez is expected to step into the closer role while Puk is out. Martinez boasts an impressive 0.90 ERA this season, demonstrating his potential as a strong replacement.