Pro Football Reference Stat Glossary

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Passer Rating Index

For each stat for each year for each league, we computed two things:

  1. the league average for that stat in that league during the three-year period with the given year in the middle. For example, the "league average" for the 1963 AFL would be the aggregate average of the stats accumulated in the AFL from 1962 to 1964. (NOTE: the 1960 AFL and the 1969 AFL, as well as the current season, will be based on only two years worth of data rather than three.)

  2. the standard deviation of the stat for all individuals who had 14 or more pass attempts per scheduled game during the three-year period.

Next, we computed how many standard deviations away from the league average each player was in each of his seasons. We multiply that number by 15 and add it to 100, and that is the number you see.

Bottom line:

  • On all stats, 100 is league average.
  • On all stats (including sack percentage and interception percentage), a higher number means better than average
  • The greatest passing seasons of all time are in the 140s. A typical league-leading season in most categories will be in the high 120s or the low-to-mid 130s.
  • Only seasons in which the player attempted 50 or more passes are included in the Advanced Passing table
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