The NFL has a strength of schedule formula that's very simple to understand ... take the opponents' records from the previous season, add up the wins and losses and calculate a percentage for all 17 opponents. In the world of fantasy football, we use a similar method. Instead of using team records, we use the number of fantasy points allowed (FPA) by defenses the previous season against a single position (both at home and on the road) and rank the teams/players according to the average.
For example, the Philadelphia Eagles allowed an average of 17 fantasy points per game to opposing quarterbacks overall last season.