Why were Mickey Mantle and Willie Mays banned from baseball?

In the 1980s, retired professional baseball players Mickey Mantle and Willie Mays were banned from professional baseball because they had side jobs working at casinos. Baseball commissioner Bowie Kuhn had both men placed on a list of "permanently ineligible" pro ball players as a result of this work.

Both of these Hall of Fame players were regarded as sports heroes by the public, and they were earning money in their retirement by trading on their fame and working as representatives of two different casinos. Whether Kuhn went too far with the ban seems to be a matter of opinion, but the next commissioner, Peter Ueberroth, disagreed with his predecessor and reinstated both players.