If you were trying to get the other team to play their cards in the 1st half, why take the ball? Why would you not defer on the coin toss to get the ball starting the second half? On average you would get more possessions in the second half, and they would be more successful due to all of the "surprises" that got thrown in at half-time. Can't buy into this theory.
So for those that think it's all about half time adjustments, please be more specific. I don't see any significant "game-plan" adjustments, certainly not that could explain the huge performance differences. Moorhead throws downfield quite often in the first half, but with less success. Though there is occasionally a different play that is successful (like the hitch-n-go we saw), it doesn't seem like there are significant differences overall.
What does seem different is the energy level. It's as if it takes a while to rotate all of the guys into the game to get them warmed up. As that's happening the other team gets worn down.