# How are Quarterback Ratings calculated?

Does anyone know the method by which NFL QB ratings are arrived at? I’ve been curious about this enigmatic statistic for a long time.

http://www.nfl.com/news/981202qbrate.html

That is from the official NFL website. I like this link better though:

http://www.nando.net/newsroom/sports/fbo/1995/nfl/nfl/stat/qbrating.html

As it simplifies things down to (mosstly) the mathematics of it all.

Having a degree in Aeronautical Engineering helps too.

Yer pal,
Satan

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Thanks for the links Satan. Found both informative, but it was the mathmatics I was looking for, and the second link cut to the chase. But I must admit that after reading about the derivation of the QB rating I must conclude that it is one of the most hard to understand statistic in pro sports.

Anyway, thanks again.

I knew that the quarterback rating system was obscure, but this is ridiculous. What the hell is this supposed to prove anyway? Add this, divide by this, subtract .02, it can’t be higher than .375… Come on, isn’t there a simpler way to figure out who’s a good quarterback and who isn’t?

The NCAA version is
Yards per attempt X 8.4

• completion percentage
• touchdown percentage X 3.3
• interception percentage X 2

It’s designed so that the average QB should score 100. The NFL system is designed so that a great QB shoud score 100.

It’s not a fan-friendly system, but the NFL and the NCAA both had trouble deciding just who was the best quarterback. So the great minds of the NFL came up with this system based on a study of past performances. The NFL decreed that it was official and that’s how the best QB would be determined. And so it was.

I was toying with the numbers. Since each step is limited to the number that can be used there (2.375) the maximum QB rating in the NFL comes to 158.33.

If those limits were not on there, and we assumed a guy threw one pass for a 99 yard TD (which seems the best possible outcome), he would get 847.9167!

Using the same criteria for someone whose only pass was picked off, the lowest one can get in reality is a big fat 0, but allowing negative numbers, we get a QB with a rating of -414.583!

Which is still slightly higher than Dave Bron when he played for my beloved Giants!

Yer pal,
Satan

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You will have, from time to time, quarterbacks who, for example, start out with a long touchdown pass and then run the ball a bunch. Their QB rating is something close to 170.xxx. I recall this happened a few weeks ago when Peyton Manning completed a pass to Marvin Harrison. 70-80 yard TD pass. His rating for the first quarter was well over 158.833.

Statistician Allen Barra (sp) has a simple method which works quite well, based on adjusted yards per pass, as follows: (passing yards - (50 X interceptions))/attempts. His theory is that an interception costs a team about 50 yards.

Small rant

Talk about stupid. The most important stat in baseball (total average) is largely ignored while the most ridiculous equation to ever spring from the human mind is used to award passing titles in the NFL. :rolleyes:

Why QB rating sucks big time?

Aside from its utter and unnecessary complexity it gives equal status to the four stats it measures: TD %, Completion %, INT % and yards per pass. Evidently, the last two are not as important.

Touchdown percentage is not that big of a deal. It depends heavily on field positon, which is accomplished via several ways other than a quaterback’s throwing prowess. Aside from rushing and return yards, it strongly relies on the defense’s ability to impede the opponent’s advance down the field. Interceptions, forced fumbles, stopping the other team on third down, they all contribute vastly to the cause of giving the offense good field position and consequently a better scoring chance.

Besides, many teams run the ball close the goal line, thus affecting the quarterback’s pass to touchdown ratio since he won’t get as many easy scores. An obvious example is Troy Aikman as opposed to Dan Marino. While Mr.Smith always gets the call close to the goal line, Marino frequently opted for the pass, rather than handing the ball to his tailback when in the endzone’s proximity.

Completion percentage doesn’t cut it either. As measured by this stat, a guy who favors short, low-degree-of-difficulty passes will be more efficient than a quarterback who is constantly looking downfield in search of the big gain. This means that it is more a reflection on a QB’s pass selection than on his throwing accuracy. If it indeed could objectively convey accuracy, then its importance would be magnified in third down situations when an incomplete pass can kill a drive or in redzone plays where a bad pass can cost a team 4 points.

The fundamental passing stat is yards per pass. it measures the ability of the QB to gain yards in an efficient fashion and as such is the most important statistic, offensive wise. It encompasses the above-criticized stats as well as INT %. This last stat also carries a great importance due to its significance from the defensive standpoint. This because a bad performance in this respect (inaccuracy, bad decision making) cedes possession of the ball to the other team, usually giving them a good offensive head start if not an immediate score. It is also relevant since it nullifies the ground already gained, either through the air or any other way.

Summarizing, make the passing rating something like this.

QB rating: 0.35yards/pass + 0.35INT% + 0.15 TD% + 0.15 * Completion%

Off to watch the Raiders game.

Any stat by itself is almost meaningless. It all depends on the kind of QB, the quality of receivers, etc. What the QB rating does is try to put it all together.

Yeah, no stat is perfect, there are many factors which evade their grasp, supporting cast being the most obvious example. Still, my critique’s intention is only to point out that, even though passer rating could never become an exact criterion regarding a QB’s efficiency, it could and should be a more representative measure of their performance.

Sorry, even if he threw 10 passes for 10 99-yard touchdowns, his rating won’t be higher than 158.33. By the built in limits, you can’t get higher than the 158.33.