Well, the reason I ask is that I was looking at the stats this morning.
First half, Oregon ran 45 plays (20 rushing, 25 passing).
Second half, Oregon ran 32 plays (24 rushing, 8 passing).
Now, I don't buy the..."they went conservative" mantra. That's not how Oregon has been and it's not how they were in the first game when they put up 77 points. We also were clearly taking over the momentum as the third quarter went on. The best way to stop that momentum is for them to keep racking up points. They would have LOVED to put up 80 points on Nebraska this weekend.
I believe Oregon was still running their offense the way they wanted to run it to put points on the board.
So, the question is, why the change. I am guessing it's because we changed how we were defending the pass. As you have pointed out, in the first half, we were making the passing game overly easy for them and they exploited that very very well.