, brother of Robin Yount, made his debut when he was 21. He was called into the game, but got hurt while warming up on the mound, and was taken out before he threw a pitch. He still got credited with a game appearance, but he never made it back to the majors.
Then you got Doc Hamann
who made his debut as a 21 year old. Came in and gave up 3 hits, 3 walks, hit a batter and thew a wild pitch. Made 0 outs and ended up with 6 earned runs. Never pitched again and ends with a career ERA of infinity.
And just as a bonus, a player named Lewis
made his debut in 1890 for the last place Buffalo Bisons who played in the Players League. His line: 3 Innings pitched, 13 hits, 7 walks, 3 HRs, 20
earned runs. Finished with a career ERA of 60. He did however manage to strike out 1 guy and even got a hit.