The Tigers placed Rodriguez on the 15-day injured list Sunday with a left rib cage sprain.
Shortly after Rodriguez was pulled from his start with left side discomfort in Wednesday's loss to the Rays, manager A.J. Hinch noted that the lefty would require a trip to the IL. The Tigers delayed making the move while awaiting the results of his MRI, which evidently revealed no oblique strain but instead an injury to his rib cage. Detroit has yet to reveal a timeline for Rodriguez's return as a result of the diagnosis, but he won't be eligible to come off the IL until early June regardless.