PFF prides itself in grading every single player on every single play at the NFL and collegiate levels on a scale of -2.0 to +2.0.
At one end of the scale, you have a catastrophic game-ending interception or pick-six from a quarterback, and at the other a perfect deep bomb into a tight window in a critical game situation, with the middle of that scale being 0-graded or “expected” plays that are neither positive nor negative. Each game is also graded by a second PFF analyst independent of the first, and those grades are compared by a Senior Analyst, who rules on any differences between the two.