 Paul Thompson, a senior quarterback-turned-wide receiver, converted back to quarterback and led the 2006 Oklahoma Sooners football team to win the Big 12 Championship Game.His departure left a void at the quarterback position at Oklahoma.Six players on the roster tried out for the starting position during the following off-season, including three walk-on quarterbacks, true freshman Keith Nichol (a Rivals.com 4-star recruit and 6th-ranked dual-threat quarterback in the 2007 recruiting class, who later transferred to Michigan State University), junior Joey Halzle (the only one with game experience), and Bradford, a redshirt freshman.