During his career, he batted and threw right-handed, stood 6 feet 2 inches (1.88 m) tall and weighed 170 pounds (77 kg).

Nicknamed "Slats", Marion had unusually long arms which reached for grounders like tentacles, prompting sportswriters to call him "The Octopus".

[4] From 1940 to 1950, Marion led the National League shortstops in fielding percentage four times, despite several other players being moved around the infield during these years.

He then moved to the American League Browns as a player-coach, and took the reins from Rogers Hornsby on June 10, 1952, as their player-manager.

Marion led the White Sox for two-plus seasons, finishing third in the American League each time, before he stepped down at the end of 1956.

In 1958, Marion purchased the Double-A minor league Houston Buffaloes from the Cardinals, and successfully moved the team to the Triple-A level under the Chicago Cubs farm system.

In 1957, Marion and business partner Milton Fischman attempted to buy the Minneapolis Lakers of the National Basketball Association from owners Ben Berger and Morris Chalfen with the intention to move the team to Kansas City, Missouri.