The NFL has become the land of the wounded/sick/retired quarterback: Foles, Darnold, Roethlisberger, Brees and Newton will all join the recently retired Andrew Luck as bystanders for at least the next week. While our PFF ELO metric accounts for the relative strengths of teams based on what happened according to our grades, it doesn’t adjust the raw number preemptively for a change in quarterback. If some teams’ rankings appear too high in light of a recent injury, that’s why.
Like any ELO system, it adjusts the ranking of a team after each game based on what happened in the game and the perceived strengths of the team and its opponent prior to the game.