Diamondbacks' Zac Gallen: cause for concern?

Gallen on the mound vs the Rays at Chase Field
Gallen on the mound vs the Rays at Chase Field / Norm Hall/GettyImages

RHP Zac Gallen has established himself as the Diamondbacks' ace ever since his breakout 2022 season. In 2022, Gallen marked a 2.54 season ERA, by far the lowest of the D-backs' rotation.

This season, Gallen came in a bit off balance, surrendering 10 runs in his first two starts before settling into a 27-inning scoreless streak and racking up 41 strikeouts in that four-start stretch.

At the end of April, his WHIP sat at an unbelievable 0.61. He's led the Cy Young odds for pretty much the entire season so far.

However, Zac's recent starts have been a bit uncharacteristic of his usual abilities. Since his 28-inning scoreless streak ended in the first inning of a May 2nd matchup with the Texas Rangers, Gallen has only had one scoreless appearance.

While you can't expect any pitcher to go 7 scoreless (innings) every single start, Gallen has allowed 34 runs (30 earned) in his last 12 starts. He's given up four or more earned runs in six starts this season.

Another less-than-ideal aspect of Gallen's game this season is the lack of soft contact outs. Zac ranks in just the 20th percentile in HardHit% this season with a bottom-10 avg exit velocity.

He's relied almost entirely on strikeouts, which falter when his control isn't there and leaves his breaking balls with a potential to hang over the plate. Home runs have also become a never-before-seen issue for the star pitcher, as he's allowed at least one per game in his last five starts, with 7 total over that period.

However, this unusual stretch of games for Gallen offers little to be genuinely concerned about. His ERA remains at a respectable 3.15, despite allowing 8 runs in his last two starts. Although he picked up the loss against the Angels in his last start, Gallen's command remained strong, and he tied his season-high with 12 Ks.

Gallen remains well above average in whiffs, K rate, and chases, and despite looking less like what we're used to seeing, history shows that the ace will likely be just fine. In fact, his 2023 campaign seems eerily similar to last year's breakout season.

In 2022, Gallen was nearly perfect through the month of May but fell behind on several rough performances once June hit. The D-backs' ace sported a lofty 5.26 for the month, going 0-2 in 5 starts.

A pair of mediocre starts in early July, and his season ERA sat at 3.40. After the all-star break, things began to click once more, and on August 2nd, his scoreless streak began. 44.1 innings later, the ace held the new Diamondbacks record for scoreless innings, passing D-backs legend Brandon Webb.

Gallen did not lose a game until September 17th--a game in which he only allowed 2 runs--and finished his season with a record of 12-4, going 7-2 after the all-star break and allowing no more than 3 runs in a single game.

Gallen had similar woes in May and June of 2023, after another hot start to the season. Despite some rough outings, however, his ERA is lower than it was at this point in the season last year, and with the all-star break coming up, we might be just weeks away from another absolutely dominant stretch of the season.

Gallen is currently 10-3, tied among starters for the 2nd most wins while being just two from matching his 2022 total. The strikeouts have also begun to roll once more.

It's also worth noting that in his recent starts, 7 of his 8 runs came in the 2nd inning of both games. In his June 27th start against the Rays, Gallen allowed 4 runs in an inauspicious 2nd but ended up pitching 4 shutout innings of two-hit ball, surviving the 6th and picking up a win behind a dominant offensive performance.

Outside of the 2nd inning in his last two starts, Zac's allowed just one run on a Mike Trout solo shot.

But it's Gallen's command that keeps him operating at a high level, even when he looks less than perfect. He's throwing first-pitch strikes to 66.2% of his faced batters, staying efficient with his pitch counts, and finding the zone with his fastball.

His lethal knuckle-curve is a destructive put-away pitch when paired with his mid-90s fastball and moving changeup, so it's been encouraging to see--even in rough starts--that his pitches are still dotting the zone, with 2/3 or more of his pitches going for strikes in most starts this season. He's also in the 92nd percentile in walks, with a stellar 120/23 K/BB. Finding the zone is no problem for Zac.

He's had a few shaky starts this year, to be sure, but he's continued to battle, racked up the Ks, and kept elite control of the zone. His WAR sits at an impressive 3.4 (per FanGraphs).

Gallen still leads the National League Cy Young race odds, although Dodgers ace Clayton Kershaw has crept up steadily behind Zac.

Kershaw has, however just landed on the IL, so a few strong starts could put Gallen up by a strong margin. Although he might have hit a few speed bumps in the season, Gallen is still the D-backs' ace, and if history has anything to show us, we're in for a special rest of the season.

(Gallen is currently scheduled to make his next start on July 8th against the Pirates.)