Posey, Cum 1988 NLS3 PSA 10 42818435.jpg
The only person in both the baseball and basketball Halls of Fame.
It's hard to know how good of a player Posey was, as he cut his playing short to take over the Homestead Grays at a fairly young age. He led his college basketball team in scoring (Holy Ghost College (Duquesne)) and played professional basketball several years. Well enough to make the HOF. He was also the captain of the Holy Ghost golf team. Cumberland Posey is an incredibly interesting man.
Edited to add: I just realized the thread was looking for non-HOFers (whoops)