Castillo is a 24-year-old from Buffalo, New York. He was selected in the 17th round out of Lancaster Central High School by the Milwaukee Brewers in 2017. He would start in the 2022 season with the Washington Wild Things of the Frontier League before making his debut with the RailCats midway through the season. He impressed in his first 47 games in Gary where he hit seven home runs and 13 doubles while finishing with a .318 batting average.

This past season, Castillo was an everyday player for the ‘Cats and was elected to the East Division All-Star team. He finished the year with a .270 average, 102 hits, and four triples.  

Castillo joins the RailCats for his seventh season in professional baseball while it will be his third on the South Shore.