This could easily go the way of the Chicago Bears season last year where they signed "veteran" QB Mike Glennon to be the interim starter until Mitch Trubisky was ready.
Trubisky had limited college experience (31 games) slightly more than Allen (27 games).
Glennon was awful (not all his fault) and was booted in favor of Trubisky week 4.
In other words, AJ McCarron could easily wind up making the case for Allen to start.