The Orioles placed Eflin on the 15-day injured list Thursday due to low-back discomfort.
Eflin will hit the shelf for the third time this season and for the second time in just over a month due to continued back problems. After being reinstated last week, Eflin made just two starts for the Orioles before suffering an apparent setback. Baltimore recalled right-hander Brandon Young from Double-A Chesapeake in a corresponding move, and he or the rehabbing Cade Povich (hip) could be called upon to replace Eflin in the rotation the next time his turn comes up.