McKeon, 80, would replace Edwin Rodriguez, who resigned yesterday with the Marlins in last place in the National League East Division. Florida has lost 10 straight games and has a 1-18 record this month.
Connie Mack was the oldest manager in baseball history, leading the Philadelphia Athletics in 1950 at age 87.
McKeon has a 1,011-940 record as a major league manager, which includes three years with the Marlins. He took over the team in 2003 after a 16-22 start and led the Marlins to a 75-49 record and a World Series title.
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