I agree that ability to get the extra possession is going to be worth several deltas of pts/possession for teams that are fairly even.
That seems to raise a question about teams having a preference for winning the coin toss and deferring. By deferring, a team is giving the opponent a chance to have an extra possession in the first half. And is more likely to end up playing from behind.
Agreed and I think it gets down to then stepping outside of just the possession math and also taking into account the other big constraint which is clock and to a lesser degree game state.
I think that middle 8 is the real world spot where they are making the bet that they can grab the extra possession (in essence) by getting ahead two scores at that spot in the game (clock constraint now) you really start to squeeze the opponent and change the efficacy of their possessions the rest of the way.
We have all seen it work a lot more than it fails.