A 6 ft 8 in (2.03 m) forward/center, he attended the University of San Francisco where he was All-Coast, All Conference & All-America and was selected by the Chicago Bulls in the second round (10th pick overall) of the 1966 NBA draft.

He attended Livermore High School, where he excelled on the basketball team under coach Leon "Lee" Williford.

[1][2][3] Mueller played college basketball at the University of San Francisco (1963-66), at both center and forward.

[7] He earned NBA All-Rookie Team honors, along with Dave Bing, Lou Hudson, Jack Marin, and Cazzie Russell.

[7][8] He was traded midway through his second season to the Los Angeles Lakers for Jim Barnes and a draft choice on January 9, 1968.