A 1942 graduate of Philadelphia's Temple University, Tomasic was the captain of the 1941 football squad and was inducted into the school's Hall of Fame in 1971.

After making his NFL debut in 1942, Tomasic did not play from 1943 to 1945, as he served in the U.S. Army during World War II.

Just before retiring from the NFL, Tomasic had already begun his professional baseball career in the minor leagues (MiLB), with the 1946 Kinston Eagles (Kinston, North Carolina), of the Coastal Plain League.

His many “farm circuit” successes earned him a big-league call-up, during the (1949) MLB season.

The New York Giants (NL) used Tomasic as a relief pitcher; over the 2 games in which he appeared, his win–loss record was 0–1, with 5 innings pitched, 10 earned runs allowed, striking out 2, while walking 5 batters.