Picking against the spread in football (is difficult)

This year I am participating in a football pool where you must pick the team that win against the spread for each week. It is much harder than picking the winning team because the spread is supposed to even out the betting money on each side is the wisdom of the crowd opinion of the score difference that has the favorite beating it 50% of the time and losing 50% of the time.

I compiled the results up to week 12 of the current season.

It hovers around the 50% mark as you might expect. But there are fluctuations, and in those fluctuations there is money to be won. As I have said, I don't know anything about football, so I have been trying to see which teams not just win, but do well (or poorly) against the spread in the hopes of figuring out which teams the bookies are having trouble with and get an edge. My results thus far are still about 50/50. I told you I don't know anything about football.