Beck attended Harrisburg Tech, located on Walnut Street. The school closed after the 1925-26 school year. In 1918 and 1919 Beck helped the Tech Maroons win back-to-back state championships in football. In 1919 Beck and the Maroons won the high school national championship. At halfback Beck score 34 touchdowns, many on long runs. He is still considered one of the greatest running backs ever developed in Pennsylvania. Beck totalled an amazing 445 points in his three years of high school. He scored six touchdowns in each of three games, and five in four more. He returned four kickoffs for touchdownss. In one 1919 game, Beck scored four touchdowns in the first seven minutes.
In 1922, the then-independent Pottsville Maroons attracted the sponsorship of several area businessmen. These men upgraded the club by luring talented pro players such as Benny Boynton, Stan Cofall and Beck to the team. In 1924 Beck helped the Maroons win the 1924 Anthracite League championship. This move placed Carl with his brother, Clarence, on the Maroons team. In 1925 the Maroons entered the NFL. That year Carl played on the Maroons team that won the 1925 NFL Championship, before it was stripped from the team due to a disputed rules violation.
In 1926 played for the Bethlehem Bears of the Eastern League of Professional Football. While with the Bears, Beck scored a touchdown in a game against Clifton Heights Black & Orange for a 10-0 Bears win. However, he and several other Bears players were mysteriously absent from the very next game against the Shenandoah Red Jackets. This move was supposedly a walk-out. As a result, manager, Gyp Downey, tried to ban all of the involved players from playing in the league. However, he withdrew his motion the very next week and the players returned to the team. In a game against the Gilberton Catamounts Carl tackled Gilberton's halfback, future-Hall of Famer, Fritz Pollard, in the open field, to preserve a 9-0 win for the Bears. The Bethlehem would finish the season in second place. Beck went on to receive first team All-Eastern League honors in 1926. While he only scored two touchdowns, including one in non-league play, for the Bears, his strong running ability was a key component of the team's success.