Are you sure you weren't playing Madden?
In all seriousness, I have never played a game on ESPN that has exceeded 56 total points (a 49-7 loss against a friend; I played like crap...) Most of my games are in the 17-24 points per team range, if not lower.
I suggest that, for the future, you might try changing your defensive playcalling, or maybe use different teams. I know that Denver has weaknesses in the secondary on ESPN, which would attribute to Denver's D not being able to stop you. As for San Fran's D, they have some good players, but they are by no means the best D on the game; if I remember correctly they have weakness in their CBs, particularly when you get into the Nickel and Dime backs. Tony Parrish is great, though.
Another idea is to fool around with the Defensive Matchup screen in gameplan. Double your opponent's best receiver, and make sure your best man is always on him in Man Coverage.