I don't think I'm old haha...definitely didn't think of Babe Ruth...was sure it was gonna be Johnson, but he was only at 19 when he turned 21
But I certainly do not understand the question....because...
Blyleven was at 26
Mathewson did it
Jim Palmer did it
CC did it
Kid Nichols did it
Vida Blue did it
maybe there are more....
but Warren Spahn didn't have ANY wins until he was 25 years old