Brandon Pfaadt's Struggles Complicate D-backs' Rotation Plans

Pfaadt's 2025 results have been fairly controversial, depending on the lens you view them with. From a straight-line results standpoint, he's been a solid bottom-of-the-rotation starter. He's pitched 5.2 innings in nine of his 12 starts and allowed four runs or fewer in 10 of them. His average game score is 48, four points below the major league average of 52. While he's been far from perfect, he's given Arizona mostly competitive starts every fifth day.

At the same time, it would be foolish to overlook the two flaws in his game that threaten to undermine his season. Those are the lack of swing-and-miss combined with the inability to prevent loud contact. The lack of bat-missing ability isn't an issue on it's own, as there are successful pitch-to-contact starters in this league. But the loud contact exacerbates that issue. Having both problems at the same time brings into question Pfaadt's ability to stick in the rotation.

The quality of contact issue is something Pfaadt will need to fix as soon as possible. He ranks in the fifth percentile in hard-hit rate, with more than half the balls put into play having an exit velocity of 95 MPH or greater. He doesn't mitigate the hard-hit contact with a heavy ground ball profile (40.7% ground ball rate), so he becomes exceptionally prone to giving up extra-base hits and home runs. He's given up 16 doubles and 17 home runs on the year.

Because of the inability to keep the bat off the barrel, Pfaadt's expected stats rank among the worst in the league. His .323 expected batting average and 6.74 expected ERA rank in the second and fourth percentiles.

Digging a bit deeper into pitch execution, it's pretty clear there's no single pitch that's been an issue. All five of his pitches have an xwOBA worse than their respective average for a right-handed major league pitcher. Per the MLB glossary, "Expected Weighted On-base Average (xwOBA) is formulated using exit velocity, launch angle and, on certain types of batted balls, Sprint Speed."

The biggest takeaway is that none of his five pitches' expected results outperform the average right-hander's expected results. Only his sinker is within 50 points.

The four-seamer, curveball, and changeup have been the biggest offenders in its performance compared to the average in terms of xwOBA. It's also worth noting that two of them (four-seamer and changeup) are where the actual results outpace the expected. Pfaadt's four-seamer wOBA (.324) outperforms his xwOBA by 133 points and the changeup (.271) by 143 points.

Pfaadt will need to fix these issues if he's to have a chance to remain an effective starter, which is critical to the team's playoff hopes. While he's signed to a five-year extension, he does have two minor league options remaining and has less than three years of service time.

Barring specific language in his contract that prevents such a move, they could send Pfaadt down to work on his execution in Triple-A. They won't do that at this time, but it's an option in the future if things don't improve.

The current rotation is in flux. Zac Gallen will start on Tuesday, followed by Merrill Kelly on Wedneday and Pfaadt on Thursday. Left-hander Eduardo Rodríguez is expected to return from the injured list during the road trip, most likely Friday or Saturday in Cincinnati.

Right-hander Corbin Burnes suffered an elbow injury in Sunday's win over the Nationals, and is probably headed to the injured list.

Ryne Nelson was moved to the bullpen, but pitched four innings on Saturday, and could possibly be inserted back into the rotation. If the team decides to stick with their plan to convert Nelson to short relief, then they could turn to either Cristian Mena or Bryce Jarvis to fill a rotation spot.

Right now, it's too early for the team to pull the plug on Pfaadt, and with all of the above going on, they simply can't afford to. He's given them competitive outings in nine of 12 starts (75%), which any team will take for their No. 5 starter. But if he has three to four more starts like he did against Washington, where consistent hard contact turns into a lot of runs, the Diamondbacks will be forced to consider more drastic measures to jump-start the team.