"Hagen filled in for the sidelined Donnie Green in the Houston, Miami, Cleveland and Baltimore games in 1974. He did an excellent job in only his second season as an offensive lineman- he switched from defense to offense late in the 1973 season.
He started four games of the 1973 season at left defensive end, made one other appearance in a reserve role and spent nine games on the inactive list. Halvor was part of the April 1973 trade with New England that also brought Jim Cheyunski and Mike Montler to Buffalo. A third round draft choice of the Dallas Cowboys in 1969, he was traded to New England in 1971.
Halvor attended Shoreline Community College for two years before moving to Weber State. He played defensive end for the Wildcats and was chosen for the Coaches All-America Game.
His hobbies are flying and skiing."
-Buffalo Bills 1975 Yearbook