Making Sense of QB Ratings

When it comes to measuring quarterbacks, the old and confusing rating system is standard. San Diego's Philip Rivers led the NFL with a 105.5 rating in 2008, but what does that mean?

At Football Outsiders, we have several proprietary ways of gauging quarterback efficiency. There are Defense-adjusted Value Over Average (DVOA) and Defense-adjusted Yards Above Replacement (DYAR) stats that measure players per play and over a full season.

Through our game-charting project, we also have a quarterback accuracy stat, which isolates what a quarterback does regardless of receivers. Since we track all errant passes, and not just those dropped or missed by receivers, we get a better idea of which quarterbacks are above the norm.

The league average for quarterback accuracy was 82.6 percent in 2008. The most accurate quarterback in 2008 based on our system was New Orleans's Drew Brees (90.2 percent).

Jason Campbell finished seventh at 85.7 percent, which means we were able to point the finger at the Redskins' beleaguered quarterback only for 14.3 percent of his incompletions.

So how'd he end up with a 62.3 percent completion rate? Ask the receivers who dropped 39 of his passes.

-- Doug Farrar

For more on Quarterback Accuracy, check out Smarter Stats at http://views.washingtonpost.com/theleague.