Stat Sheet Misconceptions: Passer Rating

| 6 years ago

Stat Sheet Misconceptions: Passer Rating

Before we move on to statistics for other positions, I think it’s necessary to examine my least favorite for quarterbacks, the Passer Rating. This number combines all of the basic statistics that are used to measure a quarterback’s passing performance into a single final figure, designed to be the ultimate evaluation for comparison’s sake. As you can see here, the Passer Rating is not the easiest number to make sense of.

According to, “in rare cases” a quarterback will have a rating over 100. In 2010 alone, Tom Brady, Philip Rivers, Aaron Rodgers and Michael Vick all accomplished this feat and ended with ratings of over 100 for the season. Vince Young was also close to this “elite” level, finishing 5th on the list with a rating of 98.64, but I doubt many teams will be fighting to bring him aboard next season.

Here we will try to make their complex formula a little easier to handle, and then we’ll take a look at the flaws of the individual parts of the formula, the flaws of the formula itself, and why we can’t use passer rating to compare eras.

What Goes Into It

When websites attempt to explain passer rating, they’ll often have a step by step process that isn’t very easy to follow. However, if you’re willing to do some algebra and make some assumptions, the formula is simpler and looks like this:

The 42 quarterbacks with the most attempts in 2010 fit the assumptions, and, in general, we don’t need to worry about them when we’re looking at a large number of attempts. However, in the interest of completeness, the assumptions are: completion percentage is between 30% and 77.5%, yards per attempt are between 3 and 12.5 yards, touchdowns are thrown on less than 11.875% of throws, and interceptions are thrown on less than 9.5% of throws. If a number is above a maximum or below a minimum, than you assume it’s the maximum or minimum value and it still works out.

The Problem With What Goes Into It

We’ve already seen that completion percentage is imperfect, and while interceptions per attempt are better than just plain interceptions, many of the same problems we discussed remain. Yards and touchdowns, in my opinion, aren’t as bad, but are both still largely dependent on situation and supporting cast. Putting them all together in a formula doesn’t make them any less flawed, so the Passer Rating incorporates all of the problems mentioned in the past two articles plus some.

What’s Worth More?

The values that were used to determine the passer rating were chosen based on league averages from years ago, but even then, they didn’t make sense. Here is an example of why:

Quarterback A throws three straight passes, completing them each for three yards. Plugging three completions, nine yards, three attempts, zero touchdowns, and zero interceptions into the equation above, and you get a quarterback rating of 97.92, which is a very good rating.

Quarterback B throws three straight passes, the first two land incomplete, and the third is caught for a 30 yard gain. Putting those numbers into the equation, you get a quarterback rating of 71.53. In the first situation, the offense is now facing fourth down, where in the second the ball just went 30 yards down field.


The first quarterback has a rating of an all pro, while the second has the rating of someone fighting for their job.
The equation is basically saying that a completion is worth as much as 20 yards, a touchdown is worth as much as 80 yards, and an interception is worth -100 yards. It makes sense that touchdowns are worth more than yards, and interceptions are negative, but, as the example illustrates, completions are very much overvalued because in reality, they only help if they gain yards.
The relative values of touchdowns and interceptions don’t make sense either. You already know that I believe the interception is overvalued as an indicator for QBs. As for touchdowns, in a game, it doesn’t matter if a quarterback were to run for one or pass for one, yet there would be a significant difference in their passer rating. I would argue a touchdown is overvalued as well.

Historic Comparison

Because of an increased number of games played in the regular season, rules opening up the passing game, and offenses simply opting to pass more often , the all-time quarterback leader boards are slowly being taken over by more recent players. This is more true for Passer Rating than any other statistic.
A look at the all time leaders shows 25 of the top 30 QB’s by Passer Rating to be players who are either still playing or who ended their carriers in the past decade. Over the years, completion percentage, yards per attempt and touchdowns have all risen while interceptions have dropped; evidence that the environment today’s QBs are playing in is significantly different than that of years past. With other statistics, you can account for era to make a more fair comparison between quarterbacks who didn’t play at the same time, but for Passer Rating this doesn’t make sense.
Chad Pennington is currently ranked as the 12th best quarterback of all time in terms of Passer Rating while Hall of Famer Joe Namath ranks 182nd. Clearly we have a problem.

Closing Thoughts

While we will never get rid of completion percentage or interceptions, the passer rating is something I sincerely hope is eliminated from stat books someday. The difference being that completions, attempts and interceptions are all things that we count, and it’s just the way the numbers have been interpreted that has become flawed.
The purpose of Passer Rating is to provide one number to use for comparing relative passing success among quarterbacks, but there are better ways to do this. Most football statistics websites have developed a version of their own by re-working the current formula. We think the PFF pass grade for quarterbacks is the best tool to use when evaluating and comparing passing performances. Whatever way you look at it though, the NFL’s Passer Rating is out of date and is no longer needed.

| Director of Analytics

Nathan has been with Pro Football Focus since 2010. He is the Director of Analytics, an NFL analyst, and a fantasy writer.

  • tim tellean

    I agree. I’ve always found catch-all made up stats like these as problematic. I think this type of stat is great for the sports writers and ESPN broadcasters, so they can speak “intelligently” to the masses.

  • PaulK

    What I get out of your “Quarterback A” rating is the importance of down and distance in evaluating passes. On first and 10, a 3 yard gain is a defensive victory. On second and 7, the quarterback is at a disadvantage and should be gambling on a lower percentage pass to try to get at least 5 yards. On third and 4, a three yard gain is actually a pretty fair try at picking up a first down. His receiver couldn’t quite stretch out. The same play, different ratings.

    As for Quarterback B, he should get demerits for first and second down flubs, the first down flub is worse, because he put the offense in a big hole. On third down I give Quarterback B major credit for a first down which is what really counts for the offense, and only slight extra credit for ripping off the extra 20 yards.

    • Nathan Jahnke

      Good point that part of that is due to down and distance when I really just wanted to illustrate how completion percentage is way over valued. It’s hard to come up with an example that doesn’t involve first downs, since there are the min/max for completion % and yards/attempt. You’re still giving more credit to Quarterback B though, and he has a significantly worse rating. I agree it should be more about getting first downs though, and that is not factored in at all in the rating, where a good number of sites including ours factors that into our/their own QB ratings.

  • jakuvious

    I think the only real problem with passer rating is people thinking it signifies more than it does. Obviously, there is no way of measuring QBs accurately, and there never will be. The only way to accurately compare QBs is to watch them yourselves and form an opinion. All in all, as long as it’s taken with a grain of salt however, I think QB rating has actually come under a bit too much scrutiny by some circles. Obviously the mass media probably overuses it, but I think some criticism more recently has become a bit too harsh, regarding the statistic, simply because there isn’t really anything better, yet. I think the problem with QB rating isn’t so much the number it creates, but the fact that you can’t really form an accurate assessment of a QB from the statistics that QB rating draws from. I mean, take the Vince Young example. 60% completion, 8.0 ypa, and a 10:3 TD/INT ratio sounds like, at the very least, a very efficient season. The problem, really, is statistics in general, more than QB rating.

    • Nathan Jahnke

      I would agree with you that there will never be a fully accurate way to measure a quarterback(or any player in any sport), but there are better ways of measuring it than others. I would definitely say that measures like our PFF rating for passing is better than QB rating. If that’s way too different for the mass media at this time, then take something like and their ANY/A. It is similar to the passer rating, but greatly improves on it. It takes out completion percentage which doesn’t need to be there, gives different numbers for the values of touchdowns and interceptions and has reasons behind them, includes sack numbers(and a metric that doesn’t include sacks if you don’t want), and doesn’t have the random number that you multiply things by or have the random constant. The flaws of it are similar to most stats in that they don’t account for situation and treat all yards and passes equal, but it’s still a step in the right direction compared to the passer rating.

      • Ramon Perez

        Sometimes delving TOO deep into the numbers is a problem as well. If you try to make 3rd down or 4th quarter passing more important (which most people try to do and claim it as being more “clutch”), you’d be saying that a QB who completes 70% of his passes on first down at 12yd/att , but only 30% of his passes on third down at 12yd/att is a lesser QB than one who completes 30% of his passes on first down and 70% on third down with the same Y/Att.

        Same goes for the quarter. If your team is losing by 20 in the 4th quarter, because of the way that you played in the first three quarters and you have a great 4th quarter, should you get extra points? If you have a bad QB rating in the 4th quarter, with your team leading by 20, because of how well you played in the first three quarters, should you be penalized?

        YAC is a tough thing to attribute to a QB, but I am certain that we can do a statistical analysis (I would personally be glad to if I had all of the data) and see how each QB’s receivers fare year by year. QBs do not have the same receivers every season, and receivers do not have the same QBs, and it wouldn’t be difficult to see how well a QB is at “leading” his receivers, or how well a receiver fares with a different QB. There should be plenty of data out there to be able to make an educated decision whether to keep all yards or not.

        Drops should definitely be removed (and spikes because there really is no way to make an argument for keeping them as incompletions), but throw aways should not. Saying that a QB should be rewarded for throwing a ball away, makes no sense. If QB 1 throws the ball away, he gets a free pass, like nothing ever happened. If QB 2 throws the ball to a receiver and the ball is batted away on an amazing play by the defender, the QB loses completion percentage and yards per attempt. Both QB 1 & QB 2 ran plays that were unsuccessful, and it should be counted that way statistically. If you want a QB accuracy rating, then create one seperately, but it does not account for total efficiency.

        It is called an “efficiency rating” because it shows how efficient the player is at his position. The completion percentage is essential because it shows the consistency of the QB. In your argument, on another page, you state that a QB who is 1-3 with a 30 yard pass has a lower rating than one who is 3-3 for 9 yards. The problem with that analysis is that it only takes into account 3 plays. QBs throughout the last 30 years routinely have over 400 plays with which to evaluate them. No one should be evaluated based on less than 1% of their plays. Look at the statistics below:

        QB 1

        280-400 70.0 3300

        QB 2

        200-400 50.0 3300

        Both QBs have identical yardage totals. QB 1 averages 11.8y/Comp, while QB 2 averages 16.5y/Comp.

        However QB 1 completes 70% of his passes, and QB 2 completes 50% of his passes. While both have identical 8.25 y/att, QB 1 gets those 8.25 yards 70% of the time, while QB 2 gets those 8.25 yards only 50% of the time. You cannot call that useless information. Consistency is important.

        Now, there are many flaws with this and any other QB rating statistic because of so many things. These statistics could be completely dismantled and looked at from absolutely every angle.

        QBs who throw the ball deep more often will have lower Comp%, higher TD%, higher Int% because they carry a much higher risk and reward, but are more difficult to complete. The ratings could be broken down by distance (Rating on throws of 0-10 yds, 11-20yds, etc.)

        The QB’s team running game/offensive line certainly helps with what types of defense the QB is throwing against and how much time he has to throw.

        The QB’s receivers could be more or less athletic than others, run better routes, have better hands, be more aggressive to the ball, etc.

        The defenses that they play against could be more or less talented than the defenses another plays against.

        No QB plays against the same defenses, with the same personnel, coaches or schemes from week to week. Sometimes a QB could play a team, let’s say the Jets, in week one and another QB could play the Jets in week 4 and they have a different game plan or different players due to injuries or changes in the lineup/scheme.

        These statistics can be broken down to: each individual pass, each individual receiver, against each individual defender, team, scheme, look, quarter, down and distance, score, opponent’s record, time left on the clock, temperature, type of stadium, etc. until everyone is happy with who comes out on top of the rankings each and every week or year.

        The reason that we don’t break it down like that is because these things average out over the 10s of thousands of passes that are thrown every year (18,301 attempts in 2015). What most statisticians look for is how much better one QBs numbers are against the rest of the league in any given season. These can be adjusted in a more vague sense without having to break it down so specifically because we have data to show what every QB does OVERALL in a season, which accounts for all of these scenarios.

        The QB rating numbers are not arbitrary, the maximums allowed were based on the all-time records for completion percentage, yards per attempt and TD%, while 0 was set to the minimum for all 4 numbers including interceptions. There is no point in going under 0, we should all be able to agree that anyone that scores a rating of 0 is not doing well.

        The statistic is extremely useful, however, if we want to account for year to year performances, and compare eras, we should not look at all-time records as the standard, but at the yearly averages. Unfortunately, ratings would bounce all over the place from week to week based on each week’s finals. So we would still need a baseline with which to work with during the season. The all-time records are a good place to start.

  • baronzbimg

    Hi guys,

    as you mas know I’m a die hard fan of this site since 2008, it is the best football analysis site in the world when it comes to evaluating players, and it already was before last offseason’s makeover, yet I strongly disagree with your analysis.

    There’s no doubt statistics don’t tell the whole story of a player’s level on the field, and passer rating for a quarterback is one of them, yet disregarding “passer rating” as “out of date and no longer needed” is just wrong.
    Passer rating is flawed, it doesn’t take into account a lot of important quarterback plays like sacks and runs for instance, but its biggest flaw is that it has virtual limits. A quarterback gets a perfect passer rating when he completes 77.5% of his passes, throws a touchdown on at least 11.875% of his attempts, gets at least 12.5 yards per pass attempted, and of course doesn’t throw an interception.
    If he completes 90% of his passes with 14 yards per attempt and 4 touchdowns on 20 attempts without an interception, he gets the same 158,3 perfect rating when it should be more than 200. If you remove the artificial limits, a quarterback who doesn’t record a “perfect game” can in fact score better than 158.3.

    Yet as flawed as it is, passer rating is one of the most amazing stat in football because it relates to the only thing that should matter: winning.

    Teams that win the passer rating battle win 80% of the time. Passer rating differential (Offensive Passer Rating minus opposite team’s passer rating) is an amazing indicator of the quality of a team.
    Last year the Packers led the league in Passer rating differential. In 2009 the Saints led the league in Passer rating differential. Passing efficiency and pass defense are the most important qualities a team must have to succeed, it has an extremely high correlation to victory throughout history.
    Bart Starr is the only quarterback to have won 5 NFL championships and he still holds today the best playoffs passer rating in NFL history (104.8 when the league average was below 80), better than Montana, Brady, Manning, Marino etc … He is a career 9-1 in the postseason, best career percentage ever. He’s the MVP of the two first Superbowls and the most underrated player in football history.

    Joe Montana holds the second best playoff passer rating in NFL history and he has won 4 Superbowls. You see a link here?

    More often than not the NFL glorifies volume numbers (passing yardage) over efficiency numbers (Yards per attempt, passer rating) whereas volume numbers tend to have no impact on the outcome of a football game. Besides the amazing play by play analysis you have here, passer rating should be the primary statistic to look at when judging a quarterback’s level of play.

    • CowboyJim

      Packer fans like me love! I used to hate passer rating, until I read all the info you mentioned at the aforementioned site. I think I hated it because I had Old Yeller fever, though. I would just like to point out that Aaron Rodgers now technically holds the mark for best career playoff passer rating. He’s got most of his career ahead of him though. Until then though I’m happy to let Bart Starr hold the reins.

      I also would like to say how much I appreciate what profootballfocus gives us and I love how there is such great analysis on football out there. I noticed that one of the writers that works here also works for coldhardfootballfacts. Maybe these two sites should pool together with the likes of to make a “quality sites” list for the average football fan.