The greatest question about Denver is who flipped the switch on their defense. That's (and playing against weak competition) the real reason they have won all their recent games.
The Tebow situation is the worse of both worlds for them. Circumstances have come about to make it so it's just enough they can't get rid of him now, even though they should. If they are lucky somebody will give a good trade for him by the beginning of next year, which probably won't happen. Otherwise Denver is screwed in the long run unless Tebow really does develop into a great quarterback before the factors that make them win despite him disappear.