Born in Wheaton, Illinois, Bollweg threw and batted left-handed; he stood 6 feet 1 inch (1.85 m) tall and weighed 190 pounds (86 kg).

[1] He resumed his playing career in 1946, spending two seasons at Double-A Houston and one at Triple-A Rochester before finally making his MLB debut at age 29 in September 1950.

On May 14, 1951, as they faced the annual roster cutdown to 25 players, the Redbirds dealt Bollweg to the New York Yankees, who sent him to the Kansas City Blues of the American Association.

That stellar Triple-A performance set the table for Bollweg's successful 1953 season as a reserve first baseman and pinch hitter for a Yankees team that captured its fifth consecutive American League pennant and World Series title.

He singled and drove in two runs as a pinch hitter in the club's first-ever home game at Municipal Stadium, but it was his only safety in nine at bats for the relocated franchise.