He played college football for the Arizona State Sun Devils.
In the AFL, Mercer played for the Oakland Raiders, the Kansas City Chiefs and the Buffalo Bills.
Mercer's 9-yard field goal attempt was blocked by Larry "Wildman" Eisenhauer and recovered by Don Webb, with about 3 minutes left, in the Oakland Raiders 43–43 tie with the Boston Patriots on October 16, 1964.
On December 22, 1963, Mercer kicked a 4th quarter 39-yard field goal to break a 49–49 tie with the Oilers and give the Raiders a 52–49 win.
This biographical article relating to an American football kicker is a stub.