You might consider Adrian Colbert the Jimmy Garoppolo of the 49ers defense.
Not only does he play free safety, the de facto quarterback of the unit who mirrors the opposition's passer, like Garoppolo Colbert never got a full understanding of the playbook at his position and excelled largely because of his instincts and physical ability.
Last year's seventh-round pick began the offseason as a cornerback, then switched to free safety after a slew of injuries hit the position. He started six games there at the end of the season and played so well that he is in line to be the starter when the 49ers visit the Minnesota Vikings in the Sept.