I think this could be a very good thing and granted, I don't know a lot about McCoy other than what I've seen this year. If he truly is a believer in Tebow, then stability at OC is a very good thing. Fox can come in and focus on the defense - fix that first and foremost - because in all honesty, if they don't ... nothing else matters.
Let Fox and the new DC do their thing on defense and let McCoy and his people continue to build up Tebow since the team is going "all in" with Tebow. In regards to helping Tebow and building the offense around him, I think there are 2 key areas to focus: another legit RB to rotate with Moreno and a solid pass-catching TE to act as the safety valve and keep the chains moving.
My two targets: DeAngelo Williams & 1 of 5 potential FA TE's (listed below)
Williams is entering his 6th season - you can find his stats here on ProFootballReference.com - the kid is young, explosive and he's obviously very familiar with Fox and McCoy (from his time in CAR). Williams is familiar with a strong RB rotation - Fox loves a strong grind it out rushing attack and with Williams and Moreno, we would have a nice duo. A strong rushing attack with continued improvement with our young OL is what Tebow will need to improve sooner rather than later.
If we can keep the current receivers in tact - Lloyd, Royal (maybe trade him to WAS if interested, although I don't like that idea a lot), Gaffney, Thomas and Decker - they can be a very solid and productive group.
What's missing? A strong pass-catching TE and who is available?
I don't know which one I would prefer, but I think any of them would be a very nice addition to this offense.
Make those 2 moves while keeping the majority of the rest in place on offense, unless you're able to upgrade without spending a ton of money, and I think the Broncos can be a very productive offense.
This would allow the new hierarchy and Fox to focus 80% of their FA and Draft on upgrading the defense. Again, nothing matters if they don't fix the defense... I don't care who the coach is or who is QB, if the defense isn't fixed, we're doomed.