Allen left the Aggies last month after a sophomore season in which he started nine of 11 games, completing better than 56 percent of his passes for 2,210 yards with 17 touchdowns and 7 interceptions. As a true freshman in 2014, Allen started five of nine games and completed better than 61 percent of his passes for 1,322 yards with 16 touchdowns and 7 picks.
Allen added 146 total rushing yards the past two years, along with three rushing touchdowns.
The 6-foot-3, 205-pound Allen was ESPN's No. 1 quarterback prospect from the Class of 2014, a four-star recruit out of Desert Mountain High in Scottsdale, Arizona.
Allen will have to sit out the 2016 season but will have two seasons of eligibility left to play at Houston beginning in 2017.
The Cougars won the American Athletic Conference this season in Tom Herman's first year as head coach, going 13-1 and capping the campaign with a New Year's Eve upset of Florida State in the Chick-fil-A Peach Bowl in Atlanta.