Acquired from the Tampa Bay Rays as a part of the larger three-team deal that brought Wil Myers to San Diego, Castillo was probably the least hyped player for any team in that deal. Signed by the Rays as an undrafted free agent out of Venezuela in July 2012, the then 17-year-old had a somewhat up and down showing with the Rays Rookie Ball affiliate in 2013. However, Castillo had an even bigger problem when he was sidelined for most of 2014 with various injuries.
Following the 2014 season, Castillo was included, along with Wil Myers and Ryan Hanigan, as part of the package exchanged in that big three-team trade. Although Castillo was probably the biggest unknown in that deal, he has slowly turned some heads as he has progressed through the Padres’ various minor league affiliates.
In his first season in the Padres’ organization, Castillo split time between short-season ball and Low-A. Castillo threw 52 and a third innings in short-season ball with a 3.61 ERA and 3.72 FIP. Although his numbers looked solid, especially his 60-plus percent ground ball rate, Castillo struggled with striking batters out, striking out only 35. Castillo finished the year with 27 innings in Low-A, but struggled with an ERA over 4.00, which looks a lot better than his FIP over 5.00 and his K-BB ratio of 16:16 (ouch).
Following his struggles in his first year in San Diego, Castillo was transitioned to a full time bullpen role. He excelled following the transition, striking out a total of 49 batters in 40 innings split between short-season ball, Low-A, and High-A. Although Castillo saw his ground ball rates decrease, his K-BB ratio vastly improved, which helped him post ERAs under 2.50 at each stop that year. Despite struggling to succeed in a starter role, Castillo finally found some traction operating in relief.
Going into 2017, Castillo was riding high after his strong showing in 2016. In fact, Castillo’s performance was good enough to earn him recognition as a member of Venezuela’s World Baseball Classic team. That selection led to one of the coolest moments of the World Baseball Classic, as Castillo got to not only pitch in front of the hometown crowd at Petco Park, but he also had made some of the biggest pitches of the whole tournament. With Venezuela holding on to a 1-0, Castillo came into the game in relief and struck out Christian Yelich and Nolan Arenado back-to-back to get his team out of the jam.
Building off that performance, Castillo began the year in High-A with the Lake Elsinore Storm, where he accumulated a 2.87 ERA over 47 innings before a late-season promotion brought him to Double-A San Antonio. Although he threw only nine and a third innings in Double-A, Castillo was just as solid, with a 2.89 ERA. Between the two levels, Castillo struck out 59 batters to just 26 walks and only gave up one home run all season. With a fastball that sits in the mid-90s and can get up to 96 or 97, as well as a slider with solid depth, Castillo has a great two-pitch mix that should allow him to continue to succeed out of the bullpen.
2018 Projection and Long-Term Outlook
With 2018 on the horizon, Castillo looks like a guy who could find himself rising quickly into the big leagues. Castillo should start the year out in Double-A and he could find himself in the big leagues before the year is over if the Padres need bullpen reinforcements. It remains to be seen how Castillo will perform at the next level, but it’s clear he has the stuff to succeed in a bullpen role.
If things work out for Castillo as he progresses through the system in 2018, he could become a fixture in the Padres’ pen for years to come. Given that the Padres added him to the 40-man roster to protect him from the Rule 5 Draft, it’s clear the team sees him having a big league future. Maybe the Padres can still win the Wil Myers’ trade after all.