The Mariners have made the biggest move of the trade deadline period to date, as Seattle acquired two-time All-Star right-handed pitcher Luis Castillo from the Cincinnati Reds on Friday. The Mariners made the deal official just after 8 p.m. Friday evening.

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ESPN’s Jeff Passan was the first to report the news, and Ryan Divish of The Seattle Times reported that the Mariners are giving up quite the haul for Castillo: top shortstop prospects Noelvi Marte and Edwin Arroyo and right-handed pitchers Levi Stoudt and Andrew Moore.

Marte (High-A Everett) and Arroyo (Single-A Modesto) are Seattle’s two top prospects, per Baseball America, and they check in at No. 1 and 3, respectively, on MLB Pipeline. Both rank in the top 100 of all MLB prospects per both publications. Stoudt (Double-A Arkansas) is a top 10 Mariners prospect while Moore (Single-A Modesto) is Seattle’s No. 26 prospect on MLB Pipeline.

As for Castillo, he’s a two-time All-Star hurler, making his first Midsummer Classic appearance in 2019 and then the National League squad again this month for the Reds. In 14 starts this year, he has a 2.86 ERA, 3.20 FIP, 1.071 WHIP and 90 strikeouts in 85 innings across 14 starts for the Reds. He owns a career 3.62 ERA since debuting in 2017.

Castillo was arguably the top available starting pitcher at this year’s deadline as an All-Star who is just 29 years old and signed through the end of 2023.

“We see Luis Castillo as an impact, top of the rotation starter who’s currently on top of his game,” Mariners president of baseball operations Jerry Dipoto said in the team’s announcement of the deal. “Our goal remains to play in the postseason, now and in the years to come. We believe adding Luis is a big step in that direction.”

During his weekly visit with The Mike Salk Show on Seattle Sports 710 AM earlier this week, Passan said that the Mariners were in on the talented right-hander. This comes a few months after the Mariners and Reds made a big offseason deal that sent All-Star left fielder Jesse Winker and All-Star third baseman Eugenio Suárez to Seattle.

The Mariners have been open about wanting to add to the rotation as rookie George Kirby is approaching uncharted territory as far as his innings go this year, and second-year hurler Logan Gilbert also just exceeded his innings total from 2021 in his Thursday start. Additionally, the Mariners have had just eight pitchers make starts this year, with two of those being bullpen days. No Mariners starter has landed on the injured list or missed a scheduled start.

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