Caissie was removed from Saturday's game against the Rays due to concussion symptoms, Jared Wyllys of AllCHGO.com reports.
Caissie's head collided with the outfield wall while he made a catch in the third inning, and manager Craig Counsell said the outfielder's condition only declined after that point. He'll enter concussion protocol and could soon be headed to the 7-day injured list, which would presumably open up playing time in the outfield for Willi Castro.