Saffold was the best guard in the NFL last year, wasn't he? He is showing no signs of wearing down, and if anything, is playing the best football of his career. I'd bet he has at the least three similar years in him, if not more. His friend to his left is pretty Damn good and quite a bit older.
Most of Saffold's injuries came when he was playing left or right tackle. He's been healthy at guard where he has less need to reach out to the side. Noteboom isn't the road grader Saffold is and like
@BonifayRam pointed out, the swingman takes a hit with Joe starting. It would be an even worse if an injury to Whitworth forces a move to OLT leaving a vacancy at left guard .Allen isn't all that tested to step into full time guard duty and couldn't be the swing tackle, and may be the starting Center. I will be surprised if we don't see another third or fourth round pick on an Olineman, in preparation for White departure. Maybe two.