Ryne Nelson's Ugly Start vs Mariners Was Extremely Discouraging

Nelson had thrown into or through the seventh inning in each of his previous four starts. He also had yet to allow more than three runs in a start since April 26 against the San Diego Padres in Mexico City.

Both of those streaks came to a screeching halt in Seattle Saturday night. Nelson was only able to muscle his way through 5.1 innings, needing a high count of 99 pitches (67 pitches) to do so. He gave up five runs, though only four were earned — one came as a result of a Jose Fernandez throwing error. His ERA rose to 4.82 on the season.

But the bigger concern was the home run ball. All four of Nelson's earned runs allowed came as the result of a solo home run — one each by Luke Raley, Colt Emerson, Julio Rodriguez and former Diamondback Dominic Canzone.

That home run problem is a red flag for Nelson. He's had some issues with the long ball in the past, but limited that type of negative outcome during his breakout 2025. Nelson allowed 0.99 home runs per nine innings in 2025, giving up just 17 homers in 154 innings — two of which came in relief.

This season, Nelson had allowed home runs at a 1.65 per nine clip heading into Saturday night. With the four solo shots, he's now surrendered 15 homers in his first 65.1 innings.

Overall, Nelson has looked like a sturdy arm on Arizona's staff this season. Despite a bit more difficulty than 2025, he's been a positive force out of the rotation. But if the home run problem continues to worsen, that will severely hinder his effectiveness.

It may partially be due to teams honing in on Nelson's four-seam fastball. As dominant an offering as that pitch has been, he's relied on it nearly 60% of the time.

Three of Nelson's homers came on a fastball, with one being an ill-placed curve. If teams are able to sit on his fastball persistently, the home runs may continue.