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Visualize this: QB Rating Explained

How exactly is the quarterback rating calculated? It’s all laid out in this week’s visual.

Chicago Bears v Pittsburgh Steelers Photo by Emilee Chinn/Getty Images

One of the most common numbers that football fans will see in any given game is the quarterback rating. Originally adopted for use by the NFL in 1973, the quarterback rating aimed to provide a better measure of quarterback play than, say, yardage totals or completion percentages.

The formula created is both straightforward and mind-numbingly silly. First, it is broken down into four calculations weighted equally, each worth 25% of the final number. The measurements chosen - completion percentage, yards per attempt, TD percentage, and interception percentage - make some level of sense. Each ratio then undergoes an adjustment factor to even things out. Those individual calculations are then added together and scaled up to the numbers we are familiar with.

A formula like this, even though it’s somewhat convoluted, is easy enough to program and calculate in real time. See this week’s visual to understand how it’s broken down into individual components and brought back together for a final calculation, including an example stat line. (For those keen observers, I used Justin Fields’s stat line from last week’s Pittsburgh game with one minor alteration to account for an officiating mistake).

Quarterback rating broken out into constituent components with a sample calculation

One of the things that has always confused me about the quarterback rating is why create a system that caps out at 158.3? We could argue that each individual component should or should not have a min or a max associated with it, but if you choose to put a cap on, why make it such a weird, random number?

My personal opinion on the quarterback rating is that it’s flawed and not really as good as a lot of people think it is but it’s not nearly as bad as many of the haters will claim. Completion percentage, yards per attempt, touchdown percentage, and interception percentage are all worthwhile statistics when it comes to quarterbacking.

The truth is that no one stat is going to tell the entire story on a per game basis. However, I do think quarterback rating can be useful over a longer term average. Certainly, a quarterback rating for the season can help tell a story because the statistic has had enough data to stabilize, which is to say one game does not provide enough data for us to feel good about the number. It’s too volatile. It probably takes about 200 attempts to stabilize quarterback rating, so a rolling average of that or a similar number would help visualize a quarterback’s play under this particular rating.

Another drawback is that it doesn’t account for sacks or what the player may contribute in the running game, let alone something like strength of opponent or wide receiver drops or the average depth of target. If we think about quarterback rating as one stat amongst many to help tell a story of a player over a chunk of time (200 passes = 5-7 games), it can be useful.

Keep the conversation on Twitter. You can find me @gridironborn.