[2] Muller competed for the United States in the 1920 Summer Olympics held in Antwerp, Belgium, in the high jump, where he won the silver medal.

Muller and six other graduates from San Diego High School later played on Cal's undefeated, untied 1920 "Wonder Team".

In the 1921 Rose Bowl, he completed a touchdown pass to Brodie Stephens that went at least 53 yards in the air.

Muller became a star end at Cal and was the first player in the western United States to receive All-American honors in 1921 and 1922.

To help supplement his income while in medical school, Andy Smith hired Muller to coach the ends on the Cal varsity.

Prior to the game, he caught a pass thrown from atop the Telephone Building—a drop of 320 feet (97.5 m).

Ed R. Hughes of the San Francisco Chronicle wrote in his column: "Remember Muller has been out of college for three years, but right now he is by far the greatest end in the West, and probably one of the best that ever played!!"