Zac Gallen has thrown 41 1/3 scoreless innings. Could the Diamondbacks pitcher break Orel Hershiser's MLB record?

It might be a September of statistical chases in MLB. Aaron Judge is gunning for 61 homers, Albert Pujols looks set to challenge 700 career home runs and Paul Goldschmidt is taking aim at the Triple Crown. Now we have to add Arizona Diamondbacks pitcher Zac Gallen to the list. His target? Orel Hershiser’s scoreless streak, 59 innings.

The 27-year-old Gallen hasn’t allowed a run in 41 1/3 innings, which is already the eighth-longest streak since 1920 (the live ball era). With one more scoreless start, he could easily leap up to the third-best streak in modern baseball history.

Gallen is set to take the mound again Sunday at Coors Field, which sounds like a daunting challenge for a scoreless streak but he already blanked the Colorado Rockies there for seven innings on Aug. 13, the second game of the six so far in his tremendous run.

Here’s what you need to know to follow Gallen’s record chase as it climbs into rarefied air.

Who is Zac Gallen?

A right-hander with an impressive mane and rec specs, Gallen is staking his claim as a budding ace. Gallen isn’t exactly new on the scene — he finished ninth in Cy Young voting in 2020 — but the Diamondbacks’ lack of contention and an injury-marred 2021 might have obscured his rising star.

A third-round pick out of the University of North Carolina in 2016, he was involved in two major trades before he lost rookie eligibility. First, he went from the St. Louis Cardinals organization to the Miami Marlins in the Marcell Ozuna deal that also netted the Marlins likely Cy Young winner Sandy Alcantara. After just seven excellent starts in the big leagues, pitching-rich Miami flipped him to Arizona in an eyebrow-raising challenge trade for shortstop Jazz Chisholm Jr.

Along with Merrill Kelly, Gallen could form the core of the rotation for the next good Diamondbacks team, which might take the field as soon as next season thanks to a wave of prospects rising out of a talented farm system.

Arizona Diamondbacks starting pitcher Zac Gallen throws a pitch against the Milwaukee Brewers during the first inning of a baseball game Sunday, Sept. 4, 2022, in Phoenix. (AP Photo/Ross D. Franklin)

Did this streak come out of nowhere?

No, Gallen has been very good from the jump despite a relative lack of prospect pedigree.

His 3.08 career ERA in 426 innings since debuting in 2019, adjusted for park and the league offensive environment, comes out to a 138 ERA+. Only eight pitchers with at least 300 innings have bested that mark over the same span.

Those numbers actually understate how great he has been most of the time. In 2019, 2020 and this season, he has posted a 150 ERA+ or better — meaning he’s been at least 50% better than the league average pitcher. Jacob deGrom, Max Scherzer and Gallen are the only hurlers to do that in three of the last four years (min. 10 starts per season).

Arguably, we should have already been talking about Gallen as one of the league’s aces, but the 2022 season is cementing his status. Working with famed pitching coach Brent Strom — who joined the Diamondbacks this offseason after years tutoring the Astros’ dominant staff — Gallen has focused on elevating his four-seam fastball more often. Sports Illustrated also reported Gallen made a mechanical adjustment on his own this offseason that contributed to increased velocity. The upshot is a trademark of other Strom pupils like Justin Verlander: Gallen flings high fastballs and then breaks off curveballs and cutters that look like the heater, only to dive toward the bottom of the zone or dart away. Even in season, Gallen has been working with Strom to fine tune his repertoire. Around the time his scoreless stretch began, he was tinkering with the changeup.

As Baseball Prospectus noted last week, the adjustments are expanding the world of possibilities hitters must consider when facing Gallen. A seemingly simple change like using the top of the zone more has exponentially complicated the task of stepping in against him thanks to his range of pitches and excellent command of them.

Can he break Orel Hershiser’s 59-inning record?

Well, obviously clearing the bar that Hershiser set for the Dodgers back in 1988 is unlikely, but it’s not impossible. FanGraphs’ Dan Szymborski, using his ZiPS projection system, estimated that Gallen has about a 2.2% chance at breaking the record. Unsurprisingly, history-making scoreless streaks are more common in low-offense environments. This season certainly qualifies.

But let’s not get ahead of ourselves. Gallen first has the Arizona team record to set, which he can do with one more clean inning. It’s currently held by Brandon Webb’s 42-inning scoreless run in 2007.

He could also claim the longest scoreless streak of the wild-card era with five more clean frames, surpassing Zack Greinke’s run of 45 2/3 innings in 2015.

Of note: Partial innings only count if the pitcher exits mid-inning and the frame ends without any runs being charged to him. So getting two outs in the first inning of his next start and then allowing a homer wouldn’t add to his current 41 1/3 innings.

If Gallen is actually going to threaten Hershiser, his greatest hurdle may be … the Dodgers. He’ll first have to get through the Rockies at Coors Sunday. Then, he would miss Diamondbacks’ series against the league’s most terrifying offense, with his next start instead lining up for Friday against the San Diego Padres.

Arizona proceeds to Los Angeles from there for five games in four days that would make the Dodgers unavoidable. He's been regularly going six or seven innings, with an occasional five-inning outing sprinkled in. If he did manage to navigate the Rockies and Padres starts with his streak intact, he could enter that potential Dodgers start within striking distance of Hershiser.

Now, the Dodgers have been demolishing even excellent pitchers, putting dents in Cy Young campaigns for the likes of Alcantara and Corbin Burnes. But maybe, just maybe, the stars are aligning for Gallen. Before Hershiser made his run to the top of the list, the record was set by Dodgers star Don Drysdale in 1968. When Hershiser broke it, Drysdale was on hand as a broadcaster. And if Gallen does make it to the precipice of the record? Well, Hershiser could be in the building. He now works as a color commentator for the Dodgers’ TV broadcasts.

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