sometimes you have to play your best kids. They redshirted a ton a guys who maybe could have helped this year, so you KNOW they are not afraid to redshirt for the future. Which leads me to believe he was ready to help more than not on special teams.
also, they could have felt he will have a HUGE impact on D this year in the secondary and wanted him to be a leader back there especially with the younger guys. now he has seen game speed and will be very valuable this year, God willing.
...one final thing, it gives incoming players a sense that if they are ready and practice the right way, they can play immediatly