The Broncos don't want a vertical passing game offense. They want a short ball control offense and running the ball. The Kubiak offense in short. That's their plan. Rely on the defense, run the ball effectively, don't get in unmanageable situations, dink and dunk.
Unless you have Aaron Rogers or Tom Brady, or Drew Brees, that kind of offense is your best bet. Minimize turnovers. Maximize field position. That's why they signed Marquette King
Why release an adequate punter in Riley Dixon and take a guy with personality issues? They are desperately trying to improve their field position game.
The signing of Case Keenum is the biggest part of that but everything points in the same direction - especially the drafting of Chubb at #5 when they already had Shane Ray and Shaqil Barrett.
They are trying to dramatically upgrade certain key positions.
Kubiak's offense like all other offenses have vertical element to them.