The Rays placed De Leon (elbow) on the 10-day disabled list Wednesday.
De Leon underwent Tommy John surgery in March and will miss the rest of the season, so it seems inevitable that he'll be moved to 60-day DL the next time the Rays need to open up a 40-man roster spot. The 25-year-old likely won't be cleared to resume throwing off flat ground until the offseason and may not be ready to go by the time the 2019 campaign opens.