A Zac Gallen Turnaround Simply Can't Wait Any Longer

The Arizona Diamondbacks have not won a series since May 26. They have an opportunity to do so on Sunday, in an early 10:40 a.m. (Arizona time) first pitch matchup with the Cincinnati Reds.

But the pitching matchup does not favor the Diamondbacks. Right-hander Zac Gallen, who was once the best arm Arizona could trot out on any given gameday, will be getting the start, hoping to avoid his third-straight poor performance.

It seems like the clock has begun to tick on Gallen, as his results continue to show signs of consistent decline. A good start Sunday would not erase the the effect of his 5.43 ERA, but it could help him return to a level that at lease provides his team a chance to win games at a more consistent rate.

Diamondbacks' Zac Gallen needs good start vs Reds

Jun 9, 2026; Miami, Florida, USA; Arizona Diamondbacks pitcher Zac Gallen (23) delivers a pitch against the Miami Marlins during the first inning at loanDepot Park. Mandatory Credit: Sam Navarro-Imagn Images | Sam Navarro-Imagn Images

The Reds are not a hot-hitting team. In fact, they've had a similarly-flat offensive output to what Arizona has been dealing with in recent days. Cincinnati only squeaked out a 2-1 win on Friday because the Diamondbacks' offensive woes were just a tick stronger.

Gallen has only faced the Reds three times, but has a 2.89 ERA in those three starts. Most recently, he delivered a strong six-inning, one-run start in late August of 2025. The Diamondbacks lost that game 6-1, but not due to any shortcoming on Gallen's part.

It was around that time of the year that Gallen, who posted a career-worst 4.83 ERA last season, had begun to show flashes of the ace-quality arm he once was. It's earlier in the season at this stage of 2026, but the turnaround has to begin now, or as close to now as possible if Arizona hopes to start consistently winning series — especially facing similar or worse opponents.

This year, Gallen's results have looked even worse. He's striking out under six batters per nine innings for a career-worst (by a wide margin)14.7% strikeout rate. He's not collecting swing-and-miss and is being hammered in the zone. His 5.52 expected ERA and 4.83 FIP do not offer much solace that his results are being unduly inflated.

"I'm not going to sit here and deny it. He's grinding. He'd be the first to tell you that it's as frustrated as he's ever been," manager Torey Lovullo said of Gallen (via Arizona Sports' Burns & Gambo). "He can't get the success or get the feel that he's had in the past."

The biggest decline in Gallen's game has been his four-seam fastball. Though still averaging a healthy 93.5 MPH, Gallen's fastball has been crushed to a .510 opposing slug, with a minuscule 7.2% whiff rate. It has declined in both location sharpness and overall deception, and that's been the case for some time.

"It's been about a year and a half, in my opinion, where he's been missing with his fastball," Lovullo said. "It's been balls that are thrown in the middle of the plate, which has led to home runs. He's given up more home runs than I think he ever, ever thought he would."

"I think he's so good at hitting lines and working edges, and that's where he's got to get his focus. He's got to get his focus on working counts, getting count leverage, and then finishing off the hitter with real good stuff."

The harsh truth is Arizona simply does not have much in the way of alternative options. Though fans may clamor for a DFA or trade, there's simply no one who could reliably replace Gallen yet.

Arizona Diamondbacks pitcher Zac Gallen — Arizona Diamondbacks right-hander Zac Gallen (23) walks back to the mound after giving up a a hit against the Los Angeles Dodgers at Chase Field in Phoenix, on June 3, 2026. | Joe Rondone/The Republic / USA TODAY NETWORK via Imagn Images

Brandon Pfaadt is being stretched back out as a starter in Reno. Cristian Mena likely won't be back this season after having shoulder surgery. Corbin Burnes' timeline has been pushed back following his setback. Lefty Mitch Bratt has yet to return from the minor league IL, and the other Triple-A starter options are all posting very poor results.

So there may not be much hope for a massive 180 out of Gallen, but that is the only way the Diamondbacks are going to get a more positive start every fifth day. Lovullo still believes in his starter, and Gallen has absolutely earned his lengthy leash, but there's no more time to waste if a serious improvement is at all possible for the former ace.

"I believe in Zac Gallen. I think he's going to turn this around. ... We don't have a lot of options in back of the group that's here right now, but Zac is Zac, and when he gets the feel, he just gets out of his way and he gets things moving in a really good direction," Lovullo said.

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