Harper was pursuing an A.J. Ellis fly ball -- which ended up being a triple -- in the bottom of the fifth inning when he apparently lost track of where he was and nailed the wall at near full speed. He appeared to hit face-first and immediately crumpled to the ground. He laid motionless for a bit, too, but eventually made his way off the field under his own power.
Here's the play:
After the game, Harper's agent Scott Boras told reporters (Amanda Comak) that Harper had received 11 stitches but somehow avoided a concussion. He also has some shoulder pain, but that appears to be the initial extent of the injuries.