I think they already have a good idea who will be the starter and may have already...or will soon make a locker room announcement. Having said that, if coaches in general tend to think that pushing off a "public" announcement works to their advantage when it comes to keeping their first opponent guessing, what better strategy to force Arizona to have to play the guessing game. Let the media and fans buzz about the most experienced QB going against the least experienced in forcing Arizona to consider different approach to their defensive strategy. If this is the case then we really shouldn't be reading much into what the coaches say to us through the media and what they let the media see in the open portions of practice. It could be Critchlow all along for all anyone but the coaches/players know.
Coaches are also known to say things publicly to try to light fires or stoke confidence in the players involved. In this case, once again there is no use in paying too much attention to what the coaches say because who ends up starting may be completely not who one anticipated based on coach speak.

Having said all this, part of the fun of being a fan is the guesswork and speculation in anticipation of the opening to the season. Just a piece of advice...save yourself the stress and frustration over being angry with the coaches because they do the whole thing different than you think they should or wish they would.