Brandon Pfaadt
The Arizona Diamondbacks recently pulled off the biggest surprise of the offseason thus far, adding Corbin Burnes to a rotation that already boasted Zac Gallen, Merrill Kelly, and Eduardo Rodriguez. Though each of these starters has an impressive track record, a former top prospect rounds out the mix and may not be an afterthought for too much longer.
Brandon Pfaadt has yet to deliver on the potential he showed in his rise to the majors, where he debuted in 2023 and put up a subpar 5.72 ERA in 96 innings. He followed that up with a mediocre sophomore season, posting a 4.71 ERA in 181.2 innings last year. So far, only his 3.27 ERA in the surprising 2023 Diamondbacks playoff run has displayed the full breadth of his potential.
However, a look under the hood shows a bright future in the desert for the 26-year-old.
While Pfaadt’s ERA was severely below league average in 2024, the ERA estimators shown above all graded out above league average. If you prefer to see the stark difference in more recognizable terms, his 4.71 ERA looks highly suspect next to his 3.61 FIP, 3.75 xERA, 3.58 xFIP, and 3.65 SIERA. By all measures, he underperformed by about a full earned run per nine innings.
Two likely culprits of his disappointing results are his poor BABIP and LOB% showings. While there is a minor amount of skill in these stats, they are largely luck-based and typically regress back to league average given enough time. It wouldn’t be surprising to see more outs on balls in play and less bunching of baserunners in 2025, leading to better results even without improvement in overall skill.
However, Pfaadt may see a bump in his skills anyway. Stuff+ and PitchingBot are two models developed by Eno Sarris and Cameron Grove, respectively, which attempt to remove extraneous factors and measure the raw ability of a pitcher’s pitches. They each have a Stuff component and a Location/Command component, which combine to give the overall (OVR) values I’m using here.
As we can see, Stuff+ and PitchingBot agree that Pfaadt’s pitch mix is already elite. That is somewhat apparent in his above-average strikeout rate and excellent ability to avoid walks, but there appears to be more room for growth. There are certainly improvements to be made to Pfaadt’s underwhelming Baseball Savant profile, after all.
When these models don’t parallel a pitcher’s results like this, it’s often because he isn’t optimally utilizing his pitches. There may be hope on the horizon, though, with new pitching coach Brian Kaplan coming to Arizona. Kaplan was previously the Assistant Pitching Coach in Philadelphia, where the Phillies led MLB in fWAR during his time in the role. Perhaps he can help Pfaadt fully realize his talent.
With a new pitching coach at the helm and four excellent starters ahead of him in the rotation to show him the ropes, Pfaadt should continue his growth into the bona fide pitcher he seems destined to be. The NL West will be a bloodbath, and Pfaadt could be a determining factor in its outcome.