Rodriguez (knee) was placed on the 15-day DL on Sunday, Jason Mastrodonato of the Boston Herald reports.
Rodriguez has progressed to live bullpen sessions in his recovery from a knee injury suffered early in spring training, but after having missed all of Grapefruit League play, he'll be unavailable for the Red Sox to begin the season. The 22-year-old will likely need to make several rehab starts in the minors to make up for the lack of spring training innings before rejoining the Red Sox, so he may not be back until early or mid-May.