Strength of Schedule
The rankings table now shows a set of columns labelled "SOS", which stands for Strength of Schedule. This is a very simple calculation where I take each team and calculate the average GPF (Generic Points Favored) of their opponents, split by games already played (the "Past" column) and by remaining games (the "Future" column). The numbers shown are in terms of GPF, with the corresponding rank beside it.
Looking at the "Past" column, the team that has played the most difficult schedule thus far is the Tennessee Titans, whose past opponents average a GPF of 2.8 (as of October 20). The team with the easiest schedule thus far is the Cincinnati Bengals, whose past opponents average a GPF of -1.9.
The Road Ahead
Looking at the "Future" column, the team with the toughest road ahead is the Arizona Cardinals, with an average opponent GPF of 2.1 points. The team with the easiest remaining schedule is the New England Patriots, whose future opponents average a GPF of -2.2 points.
One additional note: The past and future SOS numbers also account for any home field imbalances, meaning that if a team has more home games than away games remaining in its schedule, that will show up as a lower Future SOS number (with home field assumed to be worth 2.5 points).