In 1953, Junior Gilliam won the Rookie of the Year Award. He actually replaced Jackie Robinson at second base.
He played all his games at second base and none at third. Jackie was moved to the outfield that year and occasionally third base. The next season Don Hoak replaced Cox at third.
When Jackie Robinson retired at the end of the 1956 season, the New York Yankees had already promoted their first African-American player, Elston Howard in 1955 and he had hit a home run in the 1955 World Series.