It seemed like last season a new defensive back rotation was implemented every week. Outside of Richard Sherman, almost every position was up for grabs. At free safety we had several players in the mix: Adrian Colbert started the season; Jimmie Ward came in for relief once Colbert went to injured reserve; Jaquiski Tartt stood in for Ward; both ended up on IR. Antone Exum and rookie D.J. Reed also logged time at free safety this past season.
Each player has pros and cons, but the competition to me comes down to two players: Colbert and Ward.