Castillo will miss the rest of the 2019 season with a torn tendon in his left middle finger, Dennis Lin of The Athletic reports.
Castillo landed on the injured list Friday with a finger strain, but it appears he suffered a more severe injury. It's incredibly bad luck for the 23-year-old as he sustained the injury Thursday in his season debut after spending the first four-plus months of the year on the injured list. Castillo won't need to undergo surgery but will still miss the remainder of the season.