If opponents were studying tape of Tebow as the season progressed, they were also studying tape of Denver's offensive coordinator. And what they saw was coaching and play calling that was atrocious. For 3.5 quarters of each game, the OC called running plays almost exclusively on 1st and 2nd downs leaving the team in long-yardage situations a majority of the time they faced third down. It is much easier to defend the pass and the run when you know when the OC will call each. It wasn't until late in the 4th quarter that the OC would give up and just let Tebow be Tebow. And that's not just my opinion - others with more football knowledge have said the same thing.
If opponents were studying tape of Tebow as the season progressed, they were also studying tape of Denver's offensive coordinator. And what they saw was coaching and play calling that was atrocious. For 3.5 quarters of each game, the OC called running plays almost exclusively on 1st and 2nd downs
Did this tendency increase between Tebow's 7-1 start and his 1-4 finish? If not, it doesn't explain the downward trend.