The Zac Gallen Situation is Getting More Dire By the Day

The numbers just don't look good.

May 12, 2026; Arlington, Texas, USA; Arizona Diamondbacks pitcher Zac Gallen (23) waits in the dugout during the first inning against the Texas Rangers at Globe Life Field. Mandatory Credit: Andrew Dieb-Imagn Images | Andrew Dieb-Imagn Images

Arizona Diamondbacks right-hander Zac Gallen's 2026 looked, at first, like it might have been a corner-turning season. But the early-season optimism is quickly evaporating with each passing start.

That continued in a notable fashion on Tuesday night, as Gallen was knocked around by the Texas Rangers at Globe Life Field. Gallen was charged with seven earned runs (including two homers) over the course of just 4.2 innings.

Granted, there were some defensive miscues behind him. But it was a continuation of several trends that are simply becoming impossible to ignore. The truth is, Gallen simply isn't the arm he once was.

That's not to say Gallen cannot return to a certain level of dominance, or even consistent solidity. But after a career-worst season in 2025, Gallen's results and underlying metrics are telling a similar story of decline thus far this season. In fact, they're getting worse.

Diamondbacks' Zac Gallen struggling again

May 1, 2026; Chicago, Illinois, USA; Arizona Diamondbacks pitcher Zac Gallen (23) throws the ball against the Chicago Cubs during the first inning at Wrigley Field. Mandatory Credit: David Banks-Imagn Images | David Banks-Imagn Images

Gallen's ERA, after being charged with his third straight loss on Tuesday, sits at 5.65. At this time in 2025, it was 4.59. His expected ERA (5.36) and Fielding Independent Pitching (4.70) are both currently worse than how he ended 2025 (4.28 and 4.70 respectively).

Obviously, Gallen has time to get on a run, similarly to how he did in 2025 following the trade deadline. The problem is, his stuff is even less effective than it was a year ago — and significantly so.

Gallen's four-seam fastball, which has been perhaps the most glaring culprit of his poor results, is collecting just a 5% whiff rate thus far in 2026. Not only is that by far the worst figure of his career (12.9% in 2025), it's also the second-worst whiff rate on a four-seam fastball in all of major league baseball this year.

While some pitchers are able to rely primarily on pitches other than a four-seamer, it's tough for Gallen to tunnel his curveball and changeup — his top-end putaway pitches in his successful years — without at least a sturdy fastball presence.

The velocity is where it's always been, sitting 93-94. But it's currently worth -1 Run Value per Statcast. Even in a brutal 2025 season, he ended the year with a +6 Run Value.

In turn, his breaking pitches have plummeted to -8 in that department this season, with a mere 18.5% overall whiff rate on his entire arsenal. That is a bottom-10% figure in baseball, and the lack of swing-and-miss is also leading to his worst career strikeout numbers.

Zac Gallen just isn't missing bats anymore

May 7, 2026; Phoenix, Arizona, USA; Arizona Diamondbacks pitcher Zac Gallen (23) throws against the Pittsburgh Pirates in the first inning at Chase Field. Mandatory Credit: Rick Scuteri-Imagn Images | Rick Scuteri-Imagn Images

Gallen is only punching out just above six batters per nine innings. He has never dipped below 8.20 for a full season in the past.

Now, granted, strikeouts are not necessarily the only way to make a living as a pitcher. Some of the most successful arms have lived off soft contact and pitch command over whiffs — Merrill Kelly and Eduardo Rodriguez are in-house examples.

But Gallen isn't quite getting soft contact, either. His average exit velocity is 90.6, which is in the bottom quadrant of baseball. His 10.1% barrel rate and 44.6% hard-hit rate are both in a similar bottom-end range.

Manager Torey Lovullo, speaking to D-backs.TV's Jody Jackson after Gallen's most recent start, said he wants to see the right-hander work to soft contact and survive when not missing bats. That may be easier said than done.

"I want him to go out there and throw his best fastball every time and not hold back. And I want him to be aggressive when we see him do that," Lovullo said. "I've seen Zac function at a very high level for a long time. He gets pumping and it's just, it's fun to watch. He'll get back there."

Now, the one area Gallen has improved in is the ground ball. His ground ball rate is just shy of 50%, which is a career best. And to a degree, he's been getting somewhat unlucky, considering his .324 BABIP.

But that doesn't change the fact that batters are hitting the ball consistently hard off of him, nor does such a meager whiff rate bode well for the success of his entire arsenal, even if he's forced to morph into a soft-contact or ground ball-centric pitcher.

The Diamondbacks need better out of Gallen, and quickly. Whether that means a turnaround in his whiff metrics or a change in his approach and philosophy is necessary remains to be seen.