The Orioles reinstated Mountcastle (wrist) from the 10-day injured list Tuesday.
The 27-year-old has been sidelined for the past month due to a sprained left wrist, but he's ready to rejoin Baltimore after a three-game rehab assignment with Triple-A Norfolk. Mountcastle was in the midst of a 3-for-22 slump prior to the injury, and he also struggled during the rehab stint with just one hit and six strikeouts in 11 at-bats. He is not in Tuesday's lineup versus the Yankees, as Ryan O'Hearn will be at first base.