How D-backs Starter Emerged as Elite Arm in 2025

This righty was one of the bright spots of 2025.

Sep 13, 2025; Minneapolis, Minnesota, USA; Arizona Diamondbacks starting pitcher Ryne Nelson (19) throws to the Minnesota Twins in the second inning at Target Field. Mandatory Credit: Bruce Kluckhohn-Imagn Images | Bruce Kluckhohn-Imagn Images

2025 was a season full of highs and lows for the Arizona Diamondbacks, though it often seemed as if the lows took precedence after expectations were so high.

Instead, the D-backs' hopes for a playoff berth ended in an 80-82 record, beset by injuries, underperformance and an overall air of disappointment in missed opportunities.

But despite so much turmoil on Arizona's roster — particularly the pitching staff — there were some bright spots worth noting. Perhaps the biggest bright spot of all, rotationally speaking, was right-hander Ryne Nelson, who emerged as a top arm for the D-backs despite an unconventional start to the season.

As Arizona Diamondbacks On SI breaks down each individual season from the entirety of the 2025 roster, the below article will be updated with the proper links as the season reviews are published:

Related Content: Breaking Down Every Diamondbacks Player's 2025 Season

Arizona Diamondbacks 2025 Player Review: Ryne Nelson

Ryne Nelson 2025 and career statistics | Alex D'Agostino

Nelson had already showcased a bit of a breakout in the latter half of 2024. After struggling in his early days, the young righty was one of the more intriguing arms on the D-backs' staff coming into 2025.

But with the surprise addition of Corbin Burnes in the offseason, Nelson was relegated to bullpen duties. He spent his first seven appearances of the season in relief, and was shaky, pitching to a 5.82 ERA.

He was given a few fill-in opportunities to start, but when Burnes went down with Tommy John Surgery, Nelson was awarded a full-time spot in the rotation. From there, he took a leap forward.

Though it took some time to get him built back up to higher pitch counts, Nelson was one of the more reliable arms on Arizona's roster.

From June onward, he gave up more than three earned runs in an appearance only four out of his 20 starts. He pitched to a 2.22 ERA in July, and though he struggled a bit in August (4.60 monthly ERA) Nelson rebounded to deliver Quality Starts in six out of his final seven starts, with a 2.79 ERA in the month of September.

Ryne Nelson: 2026 Outlook

Arizona Diamondbacks right-hander Ryne Nelson (19) pitches against the Los Angeles Dodgers at Chase Field in Phoenix, on Sept. 24, 2025. | Joe Rondone/The Republic / USA TODAY NETWORK via Imagn Images

As long as Nelson remains healthy, he'll have a strong case to be the ace atop the D-backs' rotation alongside Merrill Kelly — at least, until Burnes comes back.

Though there has been some concern about Nelson's heavy reliance on his four-seam fastball, that offering was worth a +23 Run Value (per Statcast) carrying just a .207 opposing average against.

Related Content: Shocking Stat Proves Just How Good Ryne Nelson Was in 2025

He'll need to continue to refine his secondary pitches, no doubt. But there was progress in that department in 2025, and he appears to only be improving with time. Arizona has a legitimate weapon in their rotation in Nelson, so long as he avoids the injury bug.