Brain Snacks: Tasty Tidbits of Knowledge
Malamud said that he had to throw in all the mythological hero stuff in order for The Natural to be interesting, and not just about "baseball flat." (Source.)
Harriet Bird is loosely based on Ruth Steinhagen, a woman who lured a baseball player into her hotel room and shot him in the chest in 1949. She was committed to a mental hospital for three years. The player, Eddie Waitkus, decided not to press charges, and she spent the rest of her life living quietly in Chicago. (Source.)
In the movie version of The Natural, Robert Redford, playing Roy Hobbs, modeled his swing after Ted Williams, the player for the Boston Red Sox who's considered one of the greatest hitters of all time. Fun fact: Williams' family had him cryonically frozen after he died in 2002. His head and body are now frozen (in separate storage tanks) in Scottsdale, Arizona. (Source.)