The year before, 2006, Larsen received Second-team All-Pacific-10 Conference honors as a junior after making 89 tackles (63 solo), two sacks (11 yds.)

In 2005, he saw action in eight games (6 starts) as a sophomore and totaled 51 tackles (29 solo), one sack, one pass breakup and one fumble recovery.

Larsen did not play football from 2003–04 because he was on a mission for the Church of Jesus Christ of Latter-day Saints in Chile.

[3] On November 16, 2008, in a Broncos 24–20 road win over the Atlanta Falcons, Larsen became the first NFL player since 2003 (and only the fourth since 1990)[5] to start a game on both offense (fullback) and defense (linebacker).

Larsen earned Diet Pepsi NFL Rookie of the Week honors for the first time in his career for his performance against the Falcons.