Without a doubt, the greatest throw in baseball happened on June 5, 1989 at the old Kingdome in Seattle. The Mariners' Scott Bradley lined a double off the wall in the left field corner. On first base was Harold Reynolds, then considered the fastest man in baseball. Reynolds was off with the pitch, and was just getting to third base when the Royals' left fielder, Bo Jackson, launched a throw from the warning track. Bo's throw, a frozen rope that traveled over 310', nailed Reynolds at the plate. Insane.
https://www.youtube.com/watch?v=eB9wi_zvMdM