Predicting Diamondbacks’ biggest move before MLB trade deadline

If the Diamondbacks are going to be buyers, Hazen’s front office doesn’t have the luxury of ignoring first base any longer. The position has become a genuine liability after a carousel of disappointments.

Pavin Smith was designated for assignment on July 10 and subsequently sent outright to Triple-A Reno. Carlos Santana, signed as a veteran stopgap, saw limited action before being DFA’d. Right now, Ildemaro Vargas and Tim Tawa are splitting reps at first, hardly an intimidating tandem heading into a playoff push.

Hazen himself has acknowledged the issue and pinpointed the need for a left-handed power bat. “I probably need a little more thump in the lineup. Probably need a little more power. Probably need to get a little more left-handed,” Hazen said on MLB Network Radio. That language points directly at the first base market, and the 2026 trade landscape has some compelling options available.

The top candidate Arizona should target is Nathaniel Lowe, the left-handed first baseman currently with the Reds, who checks every box Hazen described. A proven run producer with gap power, strong on-base skills, and controllable years remaining, Lowe would represent a significant upgrade over anything Arizona currently has at the position.

Isaac Paredes of the Astros is another intriguing option, a switch-hitter with above-average pop who has been mentioned among the top first-base trade candidates leaguewide.

Bullpen Reinforcements Could Seal the Deal

Hazen’s second stated priority heading into the deadline is bullpen depth, and it’s a legitimate concern even with a solid corps already in place. The D-backs currently deploy Kevin Ginkel, Juan Morillo, A.J. Puk, Yilber Garcia, and Paul Sewald as leverage arms, a capable group, but one injury away from trouble. Adding another elite reliever could transform Arizona’s late-game reliability from average to elite.

The trade market is flush with high-leverage relief options. Luke Weaver and A.J. Minter of the Mets are listed as available, while Ryan Helsley of the Orioles would be a dream addition as a dominant closer-caliber arm.

If Arizona is prioritizing cost-controlled depth over flashy names, John Schreiber of the Royals or the Cardinals’ Riley O’Brien could provide solid eighth- or ninth-inning value without draining the prospect pipeline. The key for Hazen is making one surgical addition, not overspending on multiple arms and depleting the farm system Arizona has carefully built.

Why This Deadline Matters More Than Most

Looming over every decision Arizona makes is the injury to ace Zac Gallen, who was placed on the 15-day IL on July 12 with right elbow inflammation. Losing one of the rotation’s most reliable arms at this juncture is a significant blow, and it will factor into how aggressively Hazen moves.

The D-backs had hoped to avoid adding a starter at the deadline, but Gallen’s status adds volatility to that plan. Eduardo Rodriguez (8-3, 2.29 ERA) and Michael Soroka (8-3, 3.07 ERA) have been excellent, but depth matters in October.

The schedule coming out of the All-Star break is brutal, series against the Cardinals, A’s, Nationals, Pirates, and Guardians before the deadline arrives. If Arizona goes 5-5 or better in that stretch and remains within striking distance of a Wild Card berth, expect Hazen to pull the trigger on a first baseman and a bullpen arm.

If the team stumbles, the calculus flips entirely, and veterans like Gallen, once healthy, and potentially Eduardo Rodriguez become trade candidates for contenders. The window is open, but it is closing fast, and the Diamondbacks’ biggest move of the summer will be made in the next 18 days.