Duane Pesice put this note in Cub Tracks, but I thought you’d be interested in a few more details of the story of how Ron Santo became the first player to invoke his 10-and-5 rights under the then-new labor agreement between owners and players.
The contract clause allowed players who had 10 years of major league experience, and at least the last five with the same team, to veto any trade.
Santo, who had been a popular player over the first few years of his career, had fallen out of favor both with management and fans by the end of the 1973 season, and his production had fallen off as well.