The Packers have had Aaron Rodgers at quarterback in each of the last three seasons, but they haven’t been able to team him with the same center for that period of town. Scott Wells, Jeff Saturday and Evan Dietrich-Smith have all taken turns in the spot, leaving Rodgers to hope for “some consistentcy as far as the same guy being there for multiple years.” If 2013 fourth-round pick J.C. Tretter impresses at training camp, he could become that guy in Green Bay. Tretter broke his ankle last May and didn’t play at all for the Packers during the 2013 season, but he was activated from the PUP list in time to practice at the end of the year. His work in those practices left offensive line coach James Campen and coach Mike McCarthy happy with the progress they saw from the rookie. That didn’t stop them from bringing in competition, but Tretter feels he’s better this year than he was before the injury and plans on putting his best foot forward.