Kelly went into the 2013 season knowing full well what his QB situation was going to be and instead of making adjustments in his approach, he essentially used the same offense as before. If ever there was a time or justification to change it was last year. What did we get? Pistol and shotgun formations with empty backfields that hung a fairly immobile QB out to dry.
Instead of changing up, putting Rees under center, running the ball behind a pretty good OL, using more play action and leveraging the skill sets of the players he had, nothing changed.
As far as I am concerned, last year pretty much said it all.