Jets were trying to win a high scoring game. If the 49ers have a two or three score lead in the 2nd half they are just going to try and grind the clock, run the ball, complete 3rd down passes and make time your enemy. Taking the 49ers on large spreads is usually a bad play. Look at the Cardinals and Commies games. I think they won both of those by 6 but were up much bigger late in the game. They do tend to play prevent D kind of early which sometimes lets teams back in games.