The worst I ever saw was as a Head Varsity baseball coach, before BESR was around. We were the visiting team, I had a big ol' country boy at bat and he hit a line drive that hit the pitcher on the side of his head and then went into left center field for a double. They took the pitcher to the hospital nut he was OK.
Then on the same field not more than a week later the home team this time hits a line drive that hits the pitcher square in the nose....broke two orbital bones and multiple facial fractures, concussion out cold. The kid recovered...if you can EVER recover from that!