Every year there is an enigma that shows the weakness of the quarterback rating system.
The NFL originally standardized the current method of rating NFL quarterbacks in 1973 for the following reason (as stated on NFL.com):
"The current system, which was adopted in 1973, removes inequities that existed in the former method and, at the same time, provides a means of comparing passing performances from one season to the next."
Yet even with this effort to "remove inequities" is marked with fallacies as even the article goes on to say:
"It is important to remember that the system is used to rate passers, not quarterbacks. Statistics do not reflect leadership, play-calling, and other intangible factors that go into making a successful professional quarterback."
So with that said and done, let us move forward and explain how the current system works (In a calculator friendly manner).
As explained on NFL.com, there are four categories to the rating of an NFL Quarterback which are added together:
- Percentage of completions per attempt
- Average yards gained per attempt
- Percentage of touchdown passes per attempt
- Percentage of interceptions per attempt
It is important to note that a negative NFL Quarterback rating does not exist as the formula does not allow for a result of less than zero.
Where the article diverges and becomes non-reader friendly, I will breakdown the explanation.
Percentage of completions per attempt is (passes caught divided by passes attempted) minus .30 and then multiplied by .05 and finally multiplied by 100. The maximum result allowed is 2.375.
Average yards gained per attempt: (total passing yards divided by passes attempted) minus 3 then multiplied by .25. The maximum result allowed is 2.375
Percentage of touchdown passes: (touchdowns thrown divided by passes attempted) multiplied by .2. The maximum result is 2.375
Percentage of interceptions: (interceptions thrown divided by passing attempts) multiplied by .25, multiplied by 100, then minus this result from 2.375 (if the result, as shown on NFL.com, of interceptions thrown divided by passing attempts is 9.5 or great then the quarterback gets a zero in this category. This is because .25 multiplied by 9.5 equals 2.375 and by subtracting this result you would arrive at zero).
The above four results are added together, divided by six and then multiplied by 100. The result is the passers rating.
Fallacies in this formula (aside from the character and professionalism indicated by the NFL):
1. Dropped passes and touchdowns by receivers.
2. Interceptions caused by deflection where the deflection was not due to quarterback error (such as a bouncing out of the receivers hands).
3. Awards yardage to quarterbacks that may solely based upon receiver skill and not quarterback skill (i.e. ability to create yards solely on the receivers ability).
4. Sack yards on passing which could be a failure of the offensive line or failure of the quarterback negatively affect passing yards in both scenarios (failure of the line should not affect the QB).
5. Penalties caused by quarterback (delay of game and intentional grounding., etc.)(Should Penalty yards or penalty plays count as negative yardage or an attempt?)
6. (When errors are caused by other players, why should this count against the quarterback?) (See "unearned runs" for baseball).
Basically, even as the NFL states, the quarterback rating is far from fool-proof and does not necessarily tell a fan much about a quarterback's ability.
A bad team with lack of receivers can unfairly affect a quarterback's rating as much as a great team can make a quarterback look better.