MINNEAPOLIS -- It was the soggiest day of recent memory for the Mariners.
For the rain that soaked Target Field throughout Monday afternoon, and the performance that followed it in an 11-4 loss to the Twins.
And the downpour started and mostly ended with Luis Castillo, whose status within Seattle’s rotation is slowly but surely forecasting towards predicament.
Castillo’s day was drenched by a pair of homers and seven earned runs by the third inning, which put this one out of reach before it got going -- against a team that had lost nine of its past 10.
Maybe the skies will clear for the Mariners’ most expensive player his next turn through the rotation, but his troubling trends have eclipsed nearly a full month.
“Not frustrating at all,” Castillo said through an interpreter. “I've been in this game a long time that some things like this happen. You go through some bad stretches. All I’ve got to do is continue to throw the ball the way I've been throwing it, attacking the zone, and I know that results are going to come.”
With Bryce Miller’s return from the injured list looming, how the Mariners handle a logjam to their rotation is going to rapidly become their leading storyline.
Miller made his second rehab start on Friday night and looked great, twirling three scoreless innings with six strikeouts. He’ll climb from the 47 pitches he threw to the range of 60-65 his next time out, likely on Thursday, then roughly 75-80 after, slated for May 6, if he remains on a six-day routine.
Would that one instead come in the big leagues? It’s not a question the Mariners are ready to answer. But the even more pressing inquiry that they’re not going to broach is who would be the odd man out?
Because with a six-man rotation unlikely, this could get complicated.
“He's a veteran,” Mariners manager Dan Wilson said. “He knows adjustments that are going to be made, and understands that. And I know he continues to work.”
Castillo’s starts in 2026 have often put Seattle’s offense in a hole too big to dig out of or necessitated an improbable comeback. Outside his regular-season debut on March 30, when he threw six shutout innings vs. the Yankees, the Mariners are 1-4 behind him -- their lone victory being their largest comeback of the season, on April 11 vs. Houston.
He’s carried an 8.06 ERA in that span, second-worst among 73 pitchers who’ve made at least five starts in April, while hitters have tagged him for a 1.97 WHIP and .965 OPS, each the highest among that same group.
Monday’s conditions did him no favors, as rain sopped the mound enough that Minnesota’s grounds crew had to add Diamond Dry midgame. Precipitation also persisted all the way through the 27th out.
Those factors were likely a correlation to Castillo experiencing diminished velocity, as he was down 1.5 mph on his four-seam fastball and 2.0 mph on his sinker, both sitting in the 93-94 mph range.
Opposing hitters entered play slugging 1.000 against any heater 94 mph or lower compared to .435 against anything 95 mph or higher. Adding velocity was a pointed emphasis for him this offseason, which showed in Spring Training.
The first homer, a three-run shot from Kody Clemens, was on a 93.7 mph four-seamer. And the next, a two-run blast to Byron Buxton, was on a middle-middle slider, another pitch that’s eluded him mightily at times.
“The mound was a little wet, a little slippery,” Castillo said. “You kind of fear of sliding and maybe hitting yourself. I think it was a little combination of the weather, but I felt like when I wanted to, or felt like I needed to put a little more velocity, I felt like I could.”
Castillo is owed $24.15 million this year and next, and it’d be unprecedented for the club to just move on from him, especially this early into a season that they intend to play another six months. The Mariners know too well how quickly rotation depth can get tested, having had four arms -- including Miller -- miss significant time last year.
Castillo was their lone outlier who made each scheduled start. He’s also rebounded from an extended rough stretch like this before, just last September, and has been their most durable arm since joining the organization in 2022.
But starts like Monday’s are becoming problematic beyond the moment they happen, and tie into bigger-picture questions on Seattle’s overall rotation outlook.