At 19-years old Diego Castillo was one of the youngest players on the 2017 Charleston RiverDogs team. As many middle-infield prospects, he moved around a bit, splitting the season between second base and shortstop. The right-hander put together a solid season, facing competition that was more than three years older than him. In 118 games he hit .263/.310/.315 and drove in 42 runs. Castillo was eighth in the organization with 122 hits and fourth in at-bats.