The Mariners are finalizing an agreement to acquire reliever Diego Castillo from the Rays, reports Jeff Passan of ESPN (Twitter link). In return, Seattle is sending fellow bullpen arm JT Chargois and third base prospect Austin Shenton to Tampa Bay, reports Ryan Divish of the Seattle Times (Twitter link).
Castillo steps in, presumably, as the piece that Seattle GM Jerry Dipoto foreshadowed two days ago when the Mariners sent breakout closer Kendall Graveman to their division rival in Houston. Castillo reinforces Seattle’s bullpen not only now, but into the future. Unlike Graveman, who is a free agent at the end of the season, Castillo will remain under Seattle’s control through the 2024 season. He will be eligible for arbitration for the first time this winter.
The Rays, after all, often treat arbitration the way other franchises treat impending free agency, so it’s not a shock to see them move off Castillo, much like they did with shortstop Willy Adames earlier this season.
That said, Castillo had taken on a more premium position in Tampa’s bullpen than ever before this season, slotting in as their nominal closer. In 37 appearances, Castillo marked a 2.72 ERA/3.16 FIP across 36 1/3 innings while notching 14 saves, two more than he’d had overall in his career before the start of the season.
He’s striking out more batters than ever with a very strong 33.8 percent strikeout rate. He’s limiting free passes with a career-best 6.9 percent walk rate. The Mariners will be able to slot Castillo directly into Graveman’s vacated closer role, should they so choose.
As for the Rays, they are taking yet another opportunity to restock their farm system. Shenton was the Mariners’ 12th-ranked prospect per Baseball America. The 23-year-old third baseman started the year in High-A before earning a promotion to Double-A with a .295/.418/.576 line through 273 plate apperances.
The other piece in the deal, Chargois, should step into Castillo’s spot in the bullpen, if not his exact role. Chargois, 30, doesn’t have Castillo’s pedigree, but he’s been perhaps as effective this season, pitching to a 3.00 ERA/3.19 FIP across 30 innings for the Mariners. He’s slider-dominant with a 95.8 mph sinker to compliment, utilized more heavily against right-handers.
He seems to have figured out the control problems that plagued him in his youth. Chargois has a 5.1 percent walk rate this season after posting a double-digit percentage from 2015 through 2019 while bouncing between the upper minors and Majors with the Twins and Dodgers. As a cheap, rehabilitated arm with a keen point-of-view on the mound, Chargois fits the Rays’ profile to a tee.
More to come.