The Astros transferred McCullers (elbow) to the 60-day injured list Sunday, Chandler Rome of the Houston Chronicle reports.
The Astros determined back in November that McCullers wouldn't pitch in 2019 while recovering from Tommy John surgery, so the transaction won't affect his recovery timeline. The move merely opens up a spot on the 40-man roster for top prospect Yordan Alvarez, who was promoted from Triple-A Round Rock ahead of Sunday's game against the Orioles.