It’s all there, in the fine print. The Hall of Fame voting rules state, “Those whose careers entailed involvement in multiple categories will be considered for their overall contribution to the game of baseball,” and later cite an individual’s “record, ability, integrity, sportsmanship, character and contribution to the game.”
In other words, if, after your playing days, you become a manager and by imposing your personality of Marine discipline and quiet rectitude on a hapless franchise you transform it into one of the most celebrated World Series champions of all time, you get the extra credit.
via Hodges Added to Hall Credentials After Playing Days – NYTimes.com.