Why The Diamondbacks' Pitching Dilemma Isn't as Tough as it Looks

The Arizona Diamondbacks have a looming decision to make with regard to their starting rotation.

As right-handed veteran Merrill Kelly is set to return from the injured list during Arizona's upcoming series with the Baltimore Orioles, one of the D-backs' healthy starting pitchers will be forced out of the rotation — either to a relief role or the minor leagues.

There's not much danger for Zac Gallen, who has been the D-backs' ace and opening day starter at times through his years in Arizona. Eduardo Rodriguez has allowed one earned run in three dominant starts.

The decision comes down to the three younger arms: Ryne Nelson, Brandon Pfaadt and Michael Soroka. Nelson and Soroka both have a decent sample size of relief experience in the majors.

"We're going to figure this whole thing out, we haven't had the conversation," manager Torey Lovullo said of the roster crunch to. D-backs.TV's Jody Jackson on Saturday.

"We need to let all the dust settle, and we have some decisions to make. We have some thing that we need to start discussing very seriously."

But as tough as it may be to decide between three of pitchers the D-backs clearly believe in, there is a clear option to move out of his current role — Pfaadt. Here's why:

Why Brandon Pfaadt may be best long relief option

Mar 31, 2026; Phoenix, Arizona, USA; Arizona Diamondbacks starting pitcher Brandon Pfaadt (32) throws against the Detroit Tigers in the first inning at Chase Field. Mandatory Credit: Rick Scuteri-Imagn Images | Rick Scuteri-Imagn Images

This is not to say Pfaadt is necessarily the 'worst' pitcher of the three, nor to posit that he is untalented. He has been responsible for some of the more impressive starts by a D-backs pitcher in recent seasons — even getting very deep into games at times.

But Pfaadt has a glaring flaw — struggling with a big, blowup inning in the middle of his starts. He has often run into trouble in the fourth and fifth innings, and his career numbers represent that eye test well.

For his career, Pfaadt has a 3.54 ERA and 3.27 FIP the first time through the order. The second time through, it jumps to a 5.40 ERA and 4.01 FIP, while the third turn becomes a 7.62 ERA and 5.93 FIP. That overall trend is playing out in an even more drastic manner thus far in 2026.

Simply put, Pfaadt's excellence is more concentrated to the first two to three innings — the perfect profile of a long reliever. Pfaadt's success is often frontloaded, rather than settled into.

Why Soroka, Nelson may not be best choice to move

Arizona Diamondbacks right-hander Michael Soroka (34) reacts after striking out a batter to end the inning against the Detroit Tigers at Chase Field on March 30, 2026. | Joe Rondone/The Republic / USA TODAY NETWORK via Imagn Images

Meanwhile, Soroka has been trending in the opposite direction so far this season. The first time through the order, he's put up an 8.44 ERA (inflated by a four-run first inning in his most recent start). But from the first time through, Soroka has seemed to improve as his outings progressed.

Soroka labored through his first few innings in his D-backs debut, then ended his night with an immaculate inning and 10 strikeouts. He was blown up for four without recording an out in his second start, then went on to throw 5.2 scoreless innings, allowing the D-backs to come back.

So while Soroka may be the at-first-glance choice to move out of the rotation due to a 45.1-inning sample size in relief, he's shown an ability to be effective more than one time through an order.

His career splits as a starter give him a 3.43 ERA the first time through, but an even better 3.20 ERA the second time through. The third time through has been an uglier 6.36 figure for his career, but it's a zero so far in 2026.

As far as Nelson is concerned, he feels the least likely of the three younger arms to have his role disrupted.

Arizona already attempted to transition him from starter to reliever in 2025 with the addition of Corbin Burnes, but had to move him back into the rotation after Burnes' elbow injury. Given the injury track record of pitchers who are yanked around between roles (Drey Jameson stands out as an example), it does not feel as if the D-backs would readily force Nelson back into the bullpen.

Nelson pitched to a 3.16 ERA in 23 starts in 2025 — by far the best of Arizona's rotation come season's end. He's been the D-backs' most consistent starting pitcher since midway through 2024, and has only continued to get better.

Nelson's first two outings of 2026 were a bit rough, but he looked much more like his old self in a recent start against the Mets, pitching 5.2 innings and allowing one earned run with his plus-plus fastball.

Conclusion

Mar 27, 2026; Los Angeles, California, USA; Arizona Diamondbacks pitcher Ryne Nelson (19) pitches against the Los Angeles Dodgers in the second inning at Dodger Stadium. Mandatory Credit: Jayne Kamin-Oncea-Imagn Images | Jayne Kamin-Oncea-Imagn Images

There is certainly still a chance the Diamondbacks do still opt to send Soroka to the bullpen, given Pfaadt and Nelson's history with the organization and Soroka's overall success in relief. They may also decide to option one of Nelson or Pfaadt to Triple-A while keeping them stretched out as a starter.

But with Triple-A Reno's residence in the extremely offense-heavy Pacific Coast League, it might be detrimental to demote Pfaadt (who is on a five-year, $45 million extension) or Nelson (with his track record of consistent recent success) to the minor leagues.

In terms of skillsets and ability, moving Pfaadt to a relief role looks like the choice that could help subdue the concerns around Pfaadt's game while riding the hot hand with Soroka, who has a 2.87 ERA and 23 strikeouts in his first 15.2 innings as a D-back.