CHAPTER 16What's Wrong with the NFL QB Rating?
In Chapter 14, “Was Derek Jeter a Great Fielder?,” you learned that fielding percentage was a poor metric for measuring fielding ability. In this chapter, you will see that the NFL's well-known quarterback rating (hereafter referred to as NFL QBR) is a severely flawed measure of a quarterback's passing ability. We will use the important analytics tool of multiple regression to better understand the computation of the NFL QBR. Then we will show that evaluating the effectiveness of an NFL play by the number of points (not yards) gained or lost due to a play is vital to understanding NFL football. Finally, we will discuss ESPN's sophisticated Total Quarterback Rating (often referred to as Total QBR).
NFL Quarterback Rating
The NFL quarterback rating has been used since 1973 to rate the passing ability of NFL quarterbacks. (For the details of the formula, see en.wikipedia.org/wiki/Passer_rating). The formula, though complex, is based on four statistics:
- Completion percentage
- Yards gained per pass attempt
- TD pass percentage (fraction of pass attempts that are TDs)
- Interception percentage (fraction of passes that are interceptions)
A quarterback's passing rating will range between 0 and 158.3, and a higher rating is “thought” to be better. During every NFL game, each quarterback's QB rating is shown multiple times. As you will soon see, the QB rating system is seriously flawed. To better understand the NFL QBR system, you need to ...
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