Grissom's pro career began in 1941 in the Giants' organization, but he missed four seasons (1942-45) serving in the United States Navy during World War II [REF].
In , at age 34, Grissom finally established himself as a Major League pitcher, going 12-10 (3.74) in 28 games (24 as a starter) and 166 innings pitched, with seven complete games and one shutout.