Torii Hunter tried to score from first base on a double by Kendrys Morales that went over the head of Indians right fielder Shin-Soo Choo. Third baseman Jack Hannahan got the relay from Choo and threw to catcher Carlos Santana, who made a swipe tag on Hunter as he came in with a headfirst slide.
Hunter tried to get a piece of the plate with his hand and missed, but his left cleat caught Gibson flush on the left temple and knocked him flat. He didn't move for a few anxious moments before getting up and leaving the field under his own power after being examined by Angels trainer Rick Smith. Gibson received several stitches and was taken to a hospital for precautionary X-rays.
He was replaced behind the plate by first-base umpire Manny Gonzalez.