Oh c'mon, there wasn't a downward spiral, this team started 3-1, you're trying to act like VJ took over a losing team. Heck they even won all their preseason games for what its worth.
How does a team start 3-1 then lose 5 straight in the most terrible way ever? The games haven't even been close, every loss has been by 2+ scores, something that hasn't happened in the NFL since the 60's I believe. Opposing teams adjusted, they stacked the box on defense to stop the run game, and started playing conservative on offense, throwing often to backs and TE's. This coaching staff has FAILED miserably to make any sort of adjustments to counter what teams are doing, that's why every loss looks worse than the last, every opposing team is just copying the last game plan.
How does a team like the Jets, with the most talent stricken roster in the league, have a better record than the Broncos? Its because the Broncos problems are 100% coaching and effort by the players. For example, against New England the team quit the moment McKenzie fumbled. This is basically the same roster that won the Super Bowl 2 years ago on sheer effort with Kubiak, why was Kubiak able to get the best out of these players every week and VJ can't?