During games, pitchers threw the ball at his head.
VOA: special.2009.04.05
Then he would fall down on the floor again like a ball of dirt and start rubbing the side of his head with his back foot as if he had no idea he had been doing any more than any frog might do.
VOA: special.2009.08.29
"What has often been indicated in these studies is that people who head a lot compete to head the ball, and in those circumstances they may clash heads and get elbows to the head, which can cause concussion, " he told CNN.