"He was experiencing concussion-like symptoms," Indians manager Terry Francona said. "You talk about a lower-grade ankle, that's one thing. But, when you're talking about a concussion, you need to err on the side of caution."
In 33 games this season, Chisenhall has hit .261 with six home runs, six doubles, 22 RBIs and an .877 OPS, while bouncing between center and right field. Chisenhall started in center and went 0-for-3 on Monday against the Reds, but he was out of the lineup on Tuesday and then informed the team on Wednesday that he was not feeling right.
Francona said the team is not sure what caused the mild concussion.
"We don't know. I don't think he does, either," Francona said. "The first time he really said anything was yesterday. He felt groggy."
At the moment, the Tribe's outfield consists of Michael Brantley in left, rookie Bradley Zimmer in center and Daniel Robertson as a backup for all three spots. Austin Jackson (left big toe), Brandon Guyer (left wrist) and Abraham Almonte (right biceps) are all on the 10-day DL, though Jackson is nearing activation and could be an option for right field.
Jackson was scheduled to play in a Minor League rehab game for Triple-A Columbus on Thursday night, weather premitting.
"He's going to play right field in Columbus," Francona said. "That's the one place he really hasn't played. I told him, 'Let's just cover all the bases.' Things happen. We'd like to see Zimmer play in center as much as we can."
Jordan Bastian has covered the Indians for MLB.com since 2011, and previously covered the Blue Jays from 2006-10. Read his blog, Major League Bastian, follow him on Twitter @MLBastian and Facebook. This story was not subject to the approval of Major League Baseball or its clubs.