Allen previously held the position of assistant coach at Texas Southern University.

As a sophomore in 2008, he started 8 games in which he led the Irish in rushing with 585 yards on 134 carries (4.4 avg) and added three touchdowns.

As a junior, he only played in 8 games (7 starts) because of injury, but he was still able to lead the Irish in rushing for second straight season with 697 yards and three touchdowns on 142 carries.

In his final season as a senior, playing in only 8 games due to a hip injury, ranked second on the team in rushing with 514 yards on 107 carries (4.8) and added two touchdowns.

Allen was signed by the Tampa Bay Buccaneers as an undrafted free agent on July 27, 2011.

Allen made his debut on Christmas Day against the Green Bay Packers and rushed for 40 yards on 11 carries.