Mariners get closer Diego Castillo in trade with Rays for Chargois, prospect

Jul 29, 2021, 4:36 PM | Updated: 4:45 pm
Mariners RHP Diego Castillo...
New Mariners reliever Diego Castillo has 14 saves this year. (Getty)

Two days after trading top reliever Kendall Graveman to the Houston Astros, the Mariners have acquired his apparent replacement in the form of Diego Castillo, the closer of the Tampa Bay Rays.

Dipoto: Graveman deal had to happen when it did, ‘too good to pass up’

Reports of Seattle’s trade for the 27-year-old right hander surfaced on Twitter around 4 p.m. Thursday, with the Mariners officially announcing the deal shortly after.

Reliever JT Chargois and infield prospect Austin Shenton are the two players heading to the Rays in exchange for Castillo.

Castillo has 14 saves and a 2.72 ERA in 37 games this year for Tampa. Since making his MLB debut in 2018, he has a career 2.99 ERA and 26 saves in 167 games (183 1/3 innings). He also brings postseason experience to Seattle from his time with the Rays.

The hard-throwing Castillo ranks very well in the advanced metrics department. According to, his expected batting average (93rd percentile), expected ERA (98th percentile), expected slugging percentage (90th percentile), chase rate (95th percentile), strikeout rate (93rd percentile) and whiff rate (92nd percentile) are among the league’s best this year.

Additionally, Castillo is under club control through the 2024 season, giving the Mariners a young, high-leverage arm for the next few seasons. Fans and reportedly even some Mariners players were upset about the loss of Graveman from Tuesday’s trade, but Graveman is older (30) than Castillo and will be a free agent after this season.

As far as the players the Mariners lose in the move, Chargois has been a solid arm for Seattle’s impressive bullpen this season. The 30-year-old right-hander signed a minor league deal with the Mariners this past offseason and has a 3.00 ERA with 29 strikeouts to six walks in 30 innings this season.

Shenton is a local product, hailing from Bellingham and starring in junior college at Bellevue College. The Mariners drafted him in the fifth round of the 2019 MLB Draft. He was with Double-A Arkansas after starting the year in Single-A Everett, and between the two levels has a .300/.414/.566 slash line with 12 home runs and 61 RBIs in 67 games. Prior to the trade, Shenton was the Mariners’ No. 17-ranked prospect according to MLB Pipeline.

Follow Brandon Gustafson on Twitter.

More on the Mariners at the MLB trade deadline

O’Neil: Despite timing, Graveman trade kind of move M’s should be making
Drayer: Role M’s farm system depth could play at trade deadline
M’s Takeaways: Trade addition Abraham Toro’s strong first impression
Mariners trade prospects to Pirates for starter Tyler Anderson
Mariners send Graveman, Montero to Astros for Toro, Joe Smith
Mariners need another pitcher, so who should they target via trade?
M’s Trade Deadline: The Whit Merrifield rumor may have legs

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