HOW IT WORKS:
Pro Football Focus, which nearly a third of the NFL subscribes to, has a complex grading process, looking at every player on every offensive, defensive and special-teams play. Plus or minus grades are given and are based around an average of 0, with each position graded slightly differently. If a player does something you normally would expect, then a score of 0 is given. Grades are given for plays that are reasonably considered to be better or worse than the average or expected play. For the final grade, player participation is factored in, using a normalization factor to set the average player in that facet of the game to 0.
Compiled with Adam Jahns