Are you asking why they might not play Bryant a great deal in game two/three? His old coach Dom is the new secondary coach, I would be surprised if Bryant isn't fairly conversant with the system already.
Let's look at our current CB pool:
Veterans: Hobbs, Bryant, Webster, L. Sanders, the new cat signed after Tank's IR. I'm treating Spann as a S.
Kids: Wheatley, Wilhite, Richardson.
BB is going to keep around 5 CBs, Hobbs and Bryant seem to be locks. Wheatley looks like a lock. Richardson looked to be making the roster last season before being placed on IR, both he and Wilhite seem to have been doing okay in camp before recent injuries. L. Sanders is a career STs player, Webster is good, but has missed 12 or so practices, the new guy is a long shot. Richardson might clear waivers for the Practice Squad considering he was a low round draft pick in a poor year and dropped out of sight for a year. Right now I'd risk Richardson and keep Wilhite (not knowing injury status) and L. Sanders. That's 5, with the two rookies your nickelback contenders - I get them extra reps in preseason, especially if the vets appear to grasp the system. Hobbs started on PUP and needs to get his football conditioning back, I play him more and rest Bryant. That leaves me with three players whom I want taking extra preseason reps for various reasons, assuming Bryant is up to speed on his job. L. Sanders is garbage time STs. Those are my priorities.