Understanding NFL Quarterback Passer Rating: What It Measures and How It's Calculated

Every football fan, whether a casual observer or a die-hard NFL enthusiast, has likely encountered the term passer rating. This official measure, provided by the league, evaluates the efficiency of a quarterback's passing performance in a game. Although heavily criticized, this statistic remains a key indicator in assessing a quarterback's performance and prowess on the field.

What is Passer Rating?

The passer rating is a single number that quantifies a quarterback's efficiency. It considers four primary factors: completion percentage, yards per attempt, touchdown percentage, and interception percentage. Each of these elements is evaluated and combined to provide a holistic view of a quarterback's passing performance.

Passer Rating vs. QBR

It's crucial not to confuse passer rating with QBR, a proprietary rating system developed by ESPN. QBR (Quarterback Rating) is a specialized evaluation that accounts for a broader range of plays, considering not only passes but also rushing and other critical game situations. It operates on a 1-100 scale, where 50 represents an average performance. Elite QBRs are usually in the 80-90 range, whereas passer ratings typically fall between 90 and 105, with scores above 110 considered elite.

Calculating Passer Rating

The passer rating formula is based on a complex but not overly complicated mathematical process. Here's a step-by-step breakdown of how it is calculated:

Factor A: Completion Percentage Adjusted

First, calculate the completion percentage (completions divided by attempts). Subtract 0.3 from this ratio. Then multiply by 5. For instance, if a quarterback completes 50 out of 100 passes, their factor A is calculated as follows:

(50/100 - 0.3) * 5 1.0

Factor B: Yards Per Attempt

Next, calculate the average yards per attempt. Subtract 3.0 from this value, then multiply by 0.25. For example, a quarterback averaging 7 yards per attempt would yield:

(7 - 3) * 0.25 1.0

Factor C: Touchdowns Per Attempt

Calculate the touchdowns per attempt and multiply by 20. If a quarterback scores a touchdown once every 20 attempts, their factor C is:

(1/20) * 20 1.0

Factor D: Interceptions Per Attempt

Calculate 2.375 minus 25 times the interceptions per attempt. If the quarterback throws an interception once every 25 attempts, their factor D is:

(2.375 - (25 * 1/25)) 2.375

Combine Factors and Calculate Passer Rating

Add all four factors together, multiply by 100, and then divide by 6. The final example would look like this:

(1.0 1.0 1.0 2.375) * 100 / 6 89.58

This process yields a passer rating of 89.6. Scores around 89.6 are considered above average in the NFL.

Strengths and Weaknesses of Passer Rating

While the passer rating formula aims to provide a comprehensive measure of quarterback performance, it does have its drawbacks. The most notable limitation is that a passer rating of 100 is considered superior to an average game. Additionally, the formula heavily penalizes interceptions, making the rating more sensitive to turnover-prone quarterbacks than to those who are less likely to throw incompletions.

Overall, the passer rating remains a subject of ongoing debate in the NFL. Despite its complexities and limitations, it continues to serve as a valuable tool for fans, analysts, and front office personnel in assessing the performance of quarterbacks. Although advancements in statistical analysis have introduced more nuanced ratings like QBR, the passer rating retains its significance in the broader context of evaluating quarterback efficiency.