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Is Zac Gallen an up and coming ace?

Zac Gallen’s 2020 season was very good, the next question is if he’s a true playoff ace.

MLB: Arizona Diamondbacks at Houston Astros Troy Taormina-USA TODAY Sports

The biggest story line for the 2020 Arizona Diamondbacks, aside from the obvious disappointment in how the season unfolded, has been the break out of one of their young pitchers Zac Gallen. The D-backs originally acquired the 25-year-old starter at the 2019 Trade Deadline in exchange of one of their top prospects, Jazz Chisholm. Gallen had a solid 2019 season, with a 28% strikeout rate and a 2.81 ERA over 80 innings between the Marlins and D-backs. With how good he looked with his first taste of the majors, what would we see in his first full season?

The full season never came to fruition due to a million different reasons, as the COVID-19 outbreak combined with questionable negotiating practices for a restart shortened the season to 60 games. That meant Gallen’s encore season would only be 12 starts. Here’s how it unfolded:

12 GS, 72 IP, 2.75 ERA/3.66 FIP/3.62 xFIP, 6.9 H/9, 1.13 HR/9, 28.7% K, 8.6% BB, .271 Opp wOBA, 2.8 bWAR/1.6 fWAR

If we extrapolate this data from this 60-game season towards what he would have done in a normal season, this is what we’d get:

33 GS, 198 IP, 2.75 ERA/3.66 FIP/3.62 xFIP, 6.9 H/9, 1.13 HR/9, 28.7% K, 8.6% BB, .271 Opp wOBA, 7.7 bWAR/4.4 fWAR

With that level of production, the obvious question will be “Is Zac Gallen the new ace in Arizona?”. It very much depends on your definition of an ace. For mine, it’s a guy who you can send out there and will give you 200 innings a year, at least 60% of their starts register as quality starts (6 IP, 3 ER or less), and overall be more than 30% better than the league average pitcher at preventing runs. In 2020, Gallen averaged 6 IP per start and had quality starts in 9 of 12 (75%). In all 9 of his quality starts, Gallen gave up no more than 2 runs. In addition, his ERA- sat at 61, which means he was 39% better than the league average pitcher at preventing runs. For 2020, he checks off the boxes, but we’ll need to see him prove it over a full season’s worth of games before we can apply the Ace label to Gallen.

My expectations for Gallen at the start of the 2020 season were that he would pitch like a #3 for the first half of the season while his second half would resemble closer to #2 starter production, where I thought he’d develop long term. He’s already exceeded those expectations as he put together 8 consecutive quality starts against various AL and NL West opponents. He had a 2-inning blip where his stuff flattened out and allowed 8 runs between the 6th inning in his 9th start to the year and the first inning of his 10th start, but corrected course over the final two starts with only 2 runs allowed in 12 innings including 6 scoreless against Colorado in his final start.

What makes Gallen a difficult match-up for hitters is his ability to command four pitches that are all above-average offerings, and throw them almost equally as often. In addition to his ability to mix up pitches, Gallen threw first-pitch strikes 65% of the time in 2020. The combination of having to deal with 4 pitches on any count and starting the at-bat 0-1 already puts the hitter at a significant disadvantage. As a result, Gallen does a good job of avoiding loud contact, as he ranks in the 73rd, 77th, and 69th percentile amongst MLB pitchers in exit velocity (87.0 MPH), hard contact (32.6% of batted balls of 95+ MPH), and xwOBA (.285). Allowing soft contact will be how Gallen beats his strikeout, walk, and home run peripherals, as all the advanced metrics paint his true talent as a 3.5-3.7 ERA pitcher than his career 2.78 mark. It’ll be interesting to see where he ends up finishing closer to.

27 starts and 152 innings into his career, the possibility that Zac Gallen could develop into a Postseason Game 1 starter still very much exists. While the sample size is still relatively small, there’s no denying that his run prevention numbers put him in ace territory. We’ll have a better idea a year from now when he has about 60 starts and 350 innings under his belt. If he puts up another season with similar run prevention numbers while continuing to improve his strikeout, walk, and home run rates, the answer to that question could be a resounding yes.


Do you believe Zac Gallen has or will develop into a true ace?

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