In Mathews' four seasons at Idaho, the Vandals' first years in the Pacific Coast Conference, they won three consecutive rivalry games over Palouse neighbor Washington State. Idaho lost the other, Mathews' first in 1922, by a single point. The Vandals made significant use of the forward pass under Mathews, who was also the athletic director at Idaho.
He left Moscow and the Northwest in 1925 for St. Louis for two seasons but did not coach during the 1928 season, and worked in private business in Akron, Ohio, until hired at Gonzaga in June 1929. After less than a year in Spokane as athletic director and head coach in football and basketball, he resigned in April 1930 to pursue career options closer to the coast.
He returned to college football in Oregon at the University of Portland in 1937, where he was also athletic director. During World War II, the school dropped football prior to the 1943 season and Mathews resigned as AD the following spring when the administration extended the hiatus for the 1944 season. Entering his third season at Lewis & Clark in 1947, Mathews died on September 1 at the age of 60 of a heart attack at his home in Portland.