He made his major league debut with the Chicago Cubs on September 16, 1942. He played in four games that season, collecting one hit in 16 at-bats for a .063 batting average. In 1943, he hit .171 in 41 at-bats, with three of his seven hits being doubles.
Selected off waivers by the Chicago White Sox from the Cubs on April 20, 1946, Platt played in 84 games that year, hitting .251 with three home runs and 32 RBI in 247 at-bats. He next played in the major leagues in 1948, hitting .271 with seven home runs and 81 RBI in 123 games with the St. Louis Browns. In 1949, his final season, he hit .258 with three home runs and 29 RBI in 102 games. He played his final game on October 2, 1949.
He also played 11 seasons in the minor leagues, hitting .299 with 1,378 hits, 274 doubles, 44 triples and 95 home runs. Perhaps his best season was in 1942, when he hit .349 with 40 doubles, six triples and nine home runs.[2]
When the Browns faced black pitcher Satchel Paige of the Cleveland Indians in 1948, Platt told managerZack Taylor that he would not play against him. Taylor insisted that he play anyway. When it was Platt's turn to hit, he threw his bat at the pitcher, though Paige avoided getting whacked by it.[3]
