Mariners To Promote Blas Castano

The Mariners are recalling right-hander Blas Castano from Triple-A Tacoma, reports John Brophy. The 26-year-old righty will be making his MLB debut when he first takes the mound. The team has not announced the move or any corresponding transactions. Castano is already on the 40-man roster — Seattle selected his contract last November to shield him from being taken in the Rule 5 Draft — so the M’s only need to make a 26-man roster move to accommodate their newest call-up.

Castano, 26, was originally signed out of the Dominican Republic by the Yankees back in 2018. They released him in the summer of 2023, after which he quickly signed a minor league pact with the Mariners. He’s since solidified himself as a prospect of some note in the system. Baseball America ranked him 23rd in a deep Mariners farm heading into the year.

Though he stands at an undersized 5’10” and 162 pounds, Castano has found some success in the upper minors. He split the 2024 season between Seattle’s Double-A and Triple-A affiliates, thriving at the former (3.31 ERA) but struggling a bit at the latter (5.13 ERA, albeit in a hitter-friendly league). It evened out to a 4.38 ERA, 20% strikeout rate and 8% walk rate in 125 1/3 innings — a strong enough showing that the Mariners clearly felt a pitching-needy organization might scoop him up if given the chance in the Rule 5 Draft.

This year, Castano has better run-prevention numbers but shakier rate stats in Tacoma. He’s posted a 3.43 ERA through 44 2/3 innings, but his strikeout rate has fallen from 23.3% to 15.5%, while his walk rate has jumped from 7.6% to 10.5%. He’s also plunked four batters in those 44 2/3 innings — including three in his most recent appearance. Despite clearly spotty command that day, he still held his opponents to a run through seven innings, however.

Castano’s primary pitch is a sinker that sits 93.1 mph this season, per Statcast. He’s complemented that offering with a slider that sits 82-83 mph, a changeup that sits 87-88mph, an 89 mph cutter to help neutralize lefties and a seldom-used four-seamer that sits in the same velo range as his sinker. Baseball America’s scouting report notes that Castano’s changeup is his best secondary offering when it’s working and calls the righty a potential fifth starter or a “do-everything swingman” who can pitch in a wide variety of roles.

Mariners relievers Jesse Hahn and Eduard Bazardo threw 28 and 30 pitches yesterday, respectively, and their scheduled starter is right Emerson Hancock, who’s pitched just 9 2/3 innings across his past two starts. They could want a fresh arm to give them some length in the event of another relatively short start from Hancock, or it’s possible Castano could get a spot start if the Mariners decide to shuffle up their rotation this weekend for any reason.