Seattle Mariners reliever Diego Castillo would be a power arm in the Colorado Rockies bullpen
Diego Castillo was acquired by the Seattle Mariners from the Tampa Bay Rays last season and he has been one of the best relievers in baseball in recent years.
Castillo, who turns 28 next month, has been in the majors for under four seasons and he has had a good year in each season he has been in the majors. In 2021, he appeared in 61 games and he had an ERA of 2.78 (147 ERA+). He had a FIP of 3.47, a WHIP of 0.977, a good walk rate (2.6 BB/9), and a great strikeout rate (11.6 K/9).
In 2020 with Tampa, he had a 1.66 ERA in 22 games with a 1.062 WHIP but his walk rate was at its highest and his strikeout rate at the lowest point in his career. But in 2018 (his rookie year) and 2019, he posted ERA’s that were below 3.50 (in 108 appearances between the two seasons) with FIP’s below 3.75, an average WHIP of 1.109, a walk rate of around three per nine innings, and about 10.5 strikeouts per nine innings.
Really, the Rockies would have to have a reliever that is as consistently good as Castillo has been. He also has closing experience, as he was Tampa Bay’s closer in 2021 before they traded him to Seattle.
Since 2019 among relievers with at least 100 innings pitched, Castillo has a groundball rate of 53.6 percent, which is the 18th-highest in that span.
Castillo is eligible for arbitration for the first time this offseason and he will make roughly $2.6 million in it so Castillo could be another affordable reliever for the Rockies and a formidable one at that.
Our trade target series continues with the Texas Rangers as we wrap up the American League before heading over to the National League.