Dallas Cowboys Hagen was selected by the
Dallas Cowboys in the third round (74th overall) of the
1969 NFL/AFL draft. In his rookie season he was used as a
defensive lineman, before being switched to
offensive guard in
1970. He was a part of the
Super Bowl V team. During the
1971 offseason, because
Duane Thomas was going through a contract dispute (he requested that his 3-year contract be rewritten) and refused to report to
training camp, the Cowboys traded him to the
New England Patriots alongside Hagen and
Honor Jackson, in exchange for
Carl Garrett and the Patriots number one draft choice in the
1972 NFL draft. Within a week, because of problems with the Patriots and head coach
John Mazur, in an unprecedented move, the
NFL commissioner voided part of the trade, sending Thomas and Garrett back to their original teams. The Patriots kept Hagen and Jackson in exchange for a second and third round draft choices in the
1972 NFL draft, which the Cowboys eventually used to select
Robert Newhouse and
Mike Keller.
New England Patriots Hagen became a starter at
left guard in
1971. On April 19,
1972, he was traded along with
Jim Cheyunski and
Mike Montler to the
Buffalo Bills, in exchange for
Wayne Patrick,
Edgar Chandler and Jeff Lyman.
Buffalo Bills In
1973, he started 5 games at
left defensive end over
Walt Patulski. He was not effective as expected and was later moved to the team's
taxi squad. In
1974, he played
offensive tackle on the
offensive line that was nicknamed "
The Electric Company", when they were blocking for
O. J. Simpson. He appeared in 8 games with 4 starts. On April 9,
1976, he was traded to the
San Diego Chargers in exchange for a ninth-round draft choice (#241-Jeff Turner).
San Diego Chargers In
1976, he was moved to
offensive guard, during
training camp. On August 10, he was traded to the
New Orleans Saints in exchange for an undisclosed draft choice (not exercised).
New Orleans Saints He was released on August 26, 1976.
San Francisco 49ers On September 2,
1976, he was signed as a
free agent by the
San Francisco 49ers. He was released on September 6. ==Personal life==