Brassell was one of the few bright spots during the Rebels' dismal 2011 season. As a freshman, he was one of the only two-way players in recent program history, starting six games at receiver and another at cornerback.
He caught 24 passes for 336 yards and two touchdowns on offense. He made 14 tackles and had five pass breakups on defense.
Mississippi coach Hugh Freeze said in a statement that the staff "did all we could do to help Nick, and we wish him the very best."
Brassell sat out for the majority of the team's spring workouts so he could focus on his academics.