PEORIA, Ariz. -- The radar gun on Friday night got more of a workout than is typically customary for Luis Castillo at this time of year.
And that was by design.
The elder statesman of the Mariners’ rotation averaged 95 mph on his four-seam fastball velocity among the 20 that he threw in a 3-1 loss to the Diamondbacks at Peoria Stadium, while his sinker was at 94.9 mph on six offerings -- both nearly identical matches to his 2025 season average.
That might not sound overpowering or noteworthy. But for Castillo, who’s entering his 10th season, it’s atypical for him this early in Spring Training.
“I think the important thing for me was going out healthy and being able to attack the zone,” Castillo said through an interpreter. “That’s exactly what we saw out there, and I was super happy with what I saw. That was part of some of the training that we did in the offseason.”
Castillo has always been one to grow into his velocity as the season progresses, even during his best seasons. It’s not out of the ordinary to see him add ticks each month into the dog days, and even more so in October when reaching the postseason.
But after a 2025 in which he started to lose some heat late in the season, and with the cognizance that he’s now 33, there was a shift in his offseason regimen centered on a priority for durability -- not health-wise, but stuff-wise.
After all, he was Seattle’s lone starter who didn’t miss extended time due to an injury.
And though he didn’t deliberately say it, there was probably added motivation for how his October ended, when he was pulled after just 2 1/3 innings in Game 4 of the American League Championship Series -- the shortest of his 108 career starts in Seattle.
Overall, he had a 3.44 ERA (107 ERA+; league average is 100) and made all 32 stars. But there were also stretches of pronounced struggles -- such as a 10.06 ERA run during four outings from August into September -- that he clearly wants to avoid in ’26.
“Very long training,” Castillo said, preferring to offer specifics at a later time rather than during a standard postgame interview. “We tried to increase the velocity, but yeah, we worked a lot on it.”
On Friday, the offseason training might not have correlated to the box score -- he gave up three earned runs on four hits over 1 1/3 innings -- but this is the time of year when feel is more important than results. For context, Castillo was at 93.9 mph on his fastball in his Cactus League debut last season.
Cardio has been the primary area Castillo has honed in on throughout his career, and he’s diligent about it, regularly running the stadium steps between starts. And he added to the typical volume this winter, too.
“I think I ran 15 or 20 more miles than what I’m normally used to,” Castillo said.
Moreover, he was able to dial it up on Friday despite being delayed in Arizona -- but for the happiest of reasons, as he and his wife welcomed the birth of their third daughter.
There’s a possibility, too, that he departs camp at some point for the World Baseball Classic, as Castillo was added to the designated pitcher pool for Team Dominican Republic. Teams are allowed to make replacements from their DPP after the first round and the quarterfinals, and Castillo is one of six arms on the D.R.'s reserves.