Born in Chicago, Haffner prepped at football powerhouse Mount Carmel High School.
While at the University of Notre Dame in 1960, Haffner was awarded the starting quarterback job by head coach Joe Kuharich.
However, the team finished the season with 2–8 record, and after losing the starting job to Daryle Lamonica, Haffner transferred to McNeese State University.
Following his graduation, Haffner was selected by the Baltimore Colts with the final pick in the 1965 NFL draft.
His professional career ended with the Norfolk Neptunes of the Continental Football League, after which he returned to the college ranks as a coach.