The Broncos and Chiefs are the only teams in the AFC West that don't need great quarterback play to make the playoffs.  In the case of Siemian, the biggest knocks on him are throwing too many passes well short of the sticks and not being able to stay healthy. If the Broncos' O-line really is "fixed" (I'm still skeptical on that), then we should see huge improvement from Siemian on those two things this year plus a vastly improved running game, allowing Denver to make the playoffs.  If not, then does it matter who the QB is?  Not really.