Luis Castillo is in a tough spot in Mariners’ rotation

Of the Seattle Mariners’ five starting pitchers right now, Luis Castillo is off to the toughest start to the 2026 season.

That was apparent Monday night as Castillo allowed seven runs on seven hits and two walks over five innings in the Mariners’ 11-4 loss to the Twins in Minnesota, which raised his season ERA to 6.35, his WHIP to 1.73 and his opponent batting average to .317.

Castillo struggles as Mariners drop series opener to Twins 11-4

It’s making for a tough conversation at a time when Bryce Miller is nearing his return from the injured list, and Emerson Hancock (2.86 ERA, 0.97 WHIP, .226 opponent average) is excelling while filling Miller’s spot in the rotation.

“Unfortunately, he’s just not bringing what he was once bringing to the rotation,” Seattle Sports’ Mike Salk said Tuesday morning about Castillo, “and you are going to get Bryce Miller back sooner than later, and Emerson Hancock has made an exact opposite transformation. Emerson Hancock’s giving you what I think we all hoped Luis might give you. And Luis, unfortunately, looks like what I thought Emerson Hancock might be. If you were to strip the names off and do one of those blind taste tests, I think you’d be like, oh, OK, well, one guy belongs, one guy doesn’t. It’s pretty simple.”

At the same time, it’s tough to just write the 33-year-old Castillo off considering his durability, track record and adaptability he’s shown as he’s aged.

“I will defend him at times because I think what Luis has done is really evolve into being a different kind of pitcher,” Salk said. “When he was younger, when he first got here, he was an ace-type pitcher. If he wasn’t an ace, he was certainly a No. 1. And then something happened. He stopped having the enormous strikeout numbers, all those things changed. I think he did a really good job of just evolving into a steady presence.

“You kind of knew that every five days you were going to get a quality start, right? This was a couple of years ago, I’m not talking right now. But a couple of years ago after the true dominance ended, it was like, alright, he’s not perfect, but he doesn’t miss starts. … He’s been really steady. He takes the ball every five days.”

Salk even pointed to something from Monday’s game that was a positive, which was that Castillo still pitched through five innings, allowing Seattle to get through the game using only two pitchers out of the bullpen.

“Even last night when he stunk, he still gives you five innings so that he doesn’t absolutely torch the ‘pen,” Salk said. “They were able to go to just the (Cole) Wilcox and (Alex) Hoppe part of the ‘pen, the lowest of the leverage, in order to make sure they kept their guys healthy fresh for tonight.”

And while Castillo’s statistics through six games in 2026 are alarming, only half of those starts have been truly sub-par. He still had a sub-4.00 ERA in 2025, and while there was a rough four-game stretch in August and early September where he posted an ERA over 10.00, he followed that up by allowing just three earned runs over his final four starts of the regular season for a 1.07 ERA that helped Seattle lock up the division title.

As Maura Dooley, producer of Brock and Salk, pointed out, the rival Houston Astros would love to have a pitcher like Castillo on their staff that right now is last in MLB with a 5.97 team ERA.

“If Luis is on the Astros right now, this isn’t a conversation, right?” Dooley said.

“He’s a starting pitcher for the Astros all day,” Salk responded. “I think he can still be a pitcher in Major League Baseball, no doubt. (Of his) six starts, three of them were fine. Three of them were not, three of them were. But I think you’re looking at the longer-term trend and saying the bar to be in this rotation is just higher. It’s higher than what Luis is bringing right now.

“So I’m not going to tell you he’s washed. I honestly don’t think that. … But I do think that there’s got to be a very serious conversation, obviously.”

Catch Brock and Salk from 6-10 a.m. weekdays on Seattle Sports.

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