This topic has always interested me. I believe Nuxhall and the Chapman player were called up more as gimmicks because neither stayed up in the big leagues after their intitial call up.
The one that has always intrigued me is "Rapid Robert" Bob Feller. Called up to the big leagues from an Iowa farm at 17 years old and still a junior in hs. Who said the great ones don't come from Iowa PG
We have been talking about young Robert Stock attending USC as a junior. Imagine playing in the big leagues as a junior!
Said to have one of the greatest fast balls of all time. After his rookie season, he went back to Iowa to finish his senior season in high school. I have heard that the movie The Natural was inspired from his story. Still the only pitcher to ever throw a no hitter on opening day. Like Ted Williams, voluntarily enlisted in the service for WWII during four years of his prime which certainly prevented him from winning 300 games. Still a fan favorite in the Cleveland area to this day. A great Hall of Famer.