It also could be a reflection of the scouting department's grades on this year's QB class as well as available FAs. Maybe they're comfortable enough with Tyrod to keep him for 2-3 years and draft a QB in '18 to add to the mix.
I still think this year's plan would be Tyrod, Cheap Vet, Cardale, then next year is Tyrod, Cardale, and Rookie in a free-for-all.