Complex sentence: Despite his accomplishments, Stearnes had to work winters in Detroit's auto plants to survive, primarily in a factory owned by Walter Briggs, who was the owner of the Detroit Tigers, a team he was couldn't play for because of his skin color.
Split into simpler sentences: Despite his accomplishments, Stearnes had to work winters in Detroit's auto plants to survive. He worked in an auto factory owned by Walter Briggs, who was the owner of the Detroit Tigers, a team for which he was not allowed to play because of his skin color.