Whenever I'm watching a game with someone, I usually make a comment during the game like "that play right there is going to be huge". It could be a penalty on a key down, a turnover, a first down on 3rd and short, whatever, it could be in any quarter. For the Chicago game, I said it after Jones' second fumble. Sometimes I'm actually right ( not saying it was the CHI incident ).
I know I'm stating the obvious here, but think of those 14 point swings, team driving for a TD, defense intercepts and takes it back or scores an easy TD following. Football can be so dependent on one play, and that's what I like about it.
That's a terrible oversimplification, but you get my point.