Graterol (undisclosed) was placed on the 60-day injured list Thursday.
The 22-year-old was held back throughout spring training, and he's now set to miss the first two months of the season. The official transaction wasn't accompanied by an injury designation, so the reason for the extended absence is unclear given Graterol was throwing bullpen sessions in March. Regardless, the right-hander won't be seeing major-league action until at least the start of June.