SF Giants farm system: Updated top 31 prospect rankings

SF Giants prospects: Midseason 2021 rankings
22. Kervin Castro, RHP

Age: 22
Highest Level: Triple-A (Sacramento)
Acquired: IFA (2015)
Future-Value Grade: 40+

A breakout performance at instructs last fall quickly shot Kervin Castro up my rankings. He showed a significant jump in velocity alongside more consistency after simplifying his arsenal. Even before his jump last year, Castro was the ace of the Salem-Keizer Volcanoes, posting a 2.66 ERA across 14 starts with 61 strikeouts and just 13 walks across 67.2 innings of work back in 2019.

Primed to start 2020 at full-season ball, fans will be left wondering if he was on the cusp of becoming a premium starting pitching prospect before the pandemic took that opportunity from him.

That counterfactual should not distract SF Giants fans from Castro’s elite high-leverage upside. After moving to the bullpen, Castro has been the best and youngest pitcher on the Sacramento River Cats pitching staff this year. He’s racked up 59 strikeouts against 21 walks over 43 innings with a 2.93 ERA in an extremely hitter-friendly environment. After allowing two runs in his first appearance in June, Castro has been absolutely dominant. In his last 19 appearances, Castro has 40 strikeouts, nine walks, and a 1.69 ERA in 32 innings.

His fastball now sits in the mid-90s and occasionally reaches 98 mph, but his curveball has taken an even larger step forward since shifting to shorter outings. His once loopy breaking ball has become more refined with sharper downward movement and now routinely looks like a plus offering. Assuming he maintains his jump in velocity, he should have two above-average or better pitches.

Given his youth and impressive performance at Triple-A, I’d like to see Castro get another opportunity to stick in the rotation. The Giants have already consistently stretched him out to 40-50 pitches, which could suggest they view him as a swingman long reliever. However, he has the command and pitch arsenal to be an impact high-leverage arm as well.