Rockies Capitalize After Mariners Fail To Sneak Hot Tacoma Arm Through Waivers

What looked like a minor roster move felt like less of one once the Rockies stepped in.

Feb 19, 2026; Peoria, AZ, USA; Seattle Mariners pitcher Blas Castano (62) during spring training photo day in Peoria, AZ. Mandatory Credit: Jayne Kamin-Oncea-Imagn Images | Jayne Kamin-Oncea-Imagn Images

The Mariners knew what they were risking here. This was the kind of roster move that looked manageable until another team made sure it wasn’t. Blas Castaño had been one of Tacoma’s more effective arms to open the season, yet Seattle still had to expose him to waivers during a 40-man squeeze. A week later, the Rockies stepped in and claimed him. 

That roster move came when the Mariners selected Patrick Wisdom’s contract from Triple-A while Rob Refsnyder went on the paternity list. In the short term, the logic was easy enough to follow. Wisdom had been mashing, and Seattle needed a bat right away. But these are the trade-offs that come with roster churn, especially when the player getting squeezed was useful pitching depth. The front office clearly rolled the dice thinking it might sneak him through. It did not work. 

Rockies Snag Blas Castaño After Mariners Run Out Of Roster Room

Castaño, 27, wasn’t exactly kicking down the door to the big leagues, but he also was not giving Seattle a reason to cast him aside without consequence. With the Rainiers in 2026, he went 3-1 with a 1.42 ERA in six appearances over 6 1/3 innings, allowing just two hits and one earned run while posting a 0.47 WHIP. The fuller stat line from Tacoma was even cleaner-looking in a small sample: one walk, four strikeouts, no home runs allowed, 2.8 hits per nine innings, 1.4 walks per nine, and a 4.00 strikeout-to-walk ratio.  

It's Castaño time! #ThisIsRCity

The @Mariners selected the contract of R Blas Castaño! He's headed to The Show for the first time. Blas was 3rd in the PCL in ERA (3.43), 4th in innings pitched (44.2), 5th in opponent batting average (.240) and WHIP (1.25)

Good luck, Blas! pic.twitter.com/ZCKEWMd466

— Tacoma Rainiers (@RainiersLand) May 23, 2025

We’re not saying the Mariners just lost a hidden gem. But Seattle is a team that’s always asking its depth to matter. Castaño had fit that kind of profile better than people might realize.He was viewed as more of a contact-oriented arm than a bat-misser, with a mix built around a cutter and changeup, plus a sweeper, sinker, and four-seam fastball.  

This can probably best be viewed as a small but annoying loss rather than a devastating miscalculation. Seattle made a roster choice, prioritized immediate offense, and paid for it by losing an arm the Rockies thought was worth grabbing. Colorado immediately optioned him to Albuquerque, which tells you this was not just a paperwork move for the sake of it. They saw something worth keeping in the system.  

By September, it’s likely nobody will care. Maybe Castaño never becomes more than a journeyman depth piece. But when a pitcher is dealing, and still cannot make it through waivers, that is at least a reminder that the Mariners were not the only team paying attention.