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Smarter Stats

Quarterback Accuracy: Beyond the Ratings


When it comes to measuring quarterbacks, the old and confusing rating system has been the standard for a long time. San Diego's Philip Rivers led the NFL with a 105.5 quarterback rating in 2008, but what does that mean? It's an arbitrary number that only means something in the context of other, similar ratings. Does it mean that Rivers was 8.1 "rating points" better than Miami's Chad Pennington, who finished second at 97.4? We suppose so, but we don't really know, and it's hard to attach real value to a number without seeing the work, so to speak. Who did he throw to? Against what defenses? With how many or few defenders in the box? Was he helped or victimized by his teammates?

At Football Outsiders, we have several proprietary ways of gauging quarterback efficiency. There are our DVOA and DYAR stats, which measure players per play and over a full season. Perhaps the most important aspect of those two concepts is that they adjust for opponent - there's no statistical reward for beating up on the pass defenses of the Lions or Rams. Through our game-charting project, in which an army of volunteers and staffers track every play of every game, we also have our Quarterback Accuracy stat. This isolates what a quarterback does regardless of his receivers. Since we track all passes which are errantly (under- and over-) thrown, and not just dropped or missed by receivers, we get a better idea of which quarterbacks are really above the norm. Quarterback accuracy is the percentage of passes (minimum 200) which are not marked by our charters as Thrown Ahead, Thrown Behind, Overthrown,

The league average for Quarterback Accuracy was 82.6 percent in 2008, putting 17.3 percent of the average quarterback's incompletions on his own head. The most accurate quarterbacks in 2008 based on our system were New Orleans' Drew Brees (90.2 percent), Indianapolis' Peyton Manning (87.0), Brett Favre of the New York Jets (86.7), Arizona's Kurt Warner (86.5), and Tampa Bay's Jeff Garcia (86.0). Washington's Jason Campbell finished seventh at 85.7 percent, which means that we were only able to point the finger at the Redskins' beleaguered quarterback for 14.3 percent of his incompletions. Where's the extra 23.4 percent incompletion rate that makes up his 62.3 percent completion rate overall? Ask the receivers who dropped 39 of his passes, the highest from any quarterback in the NFL.

On the downside of this list, you'll find Oakland's JaMarcus Russell (73.5 percent - the worst among all quarterbacks with 200 or more passes), Seattle's Matt Hasselbeck (77.0), Detroit's Dan Orlovsky (77.8), Cleveland's Derek Anderson (77.8), and San Francisco's J.T. O'Sullivan. Hasselbeck is a bit of a surprise, until you remember that all his receivers were hurt last year and his offensive line was nonexistent. Another surprise is Atlanta's Matt Ryan at 79.0 percent, sixth-worst in the league (Baltimore's Joe Flacco, his rookie compatriots, finished at 81.5 percent).

Who were the primary culprits in each category? Anderson overthrew a full 9.0 percent of his passes, followed by Minnesota's Gus Frerotte (8.1), Pittsburgh's Ben Roethlisberger (7.8), Hasselbeck (7.8), and San Francisco's Shaun Hill (7.5). Brees had the fewest overthrows (2.6 percent), followed by San Diego's Philip Rivers (3.0), Jake Delhomme of the Panthers (3.2 - this was obviously before he turned into the football equivalent of Chuck Knoblauch), Miami's Chad Pennington (3.2), and Denver's Jay Cutler (3.3).

We're not sure if it's the preponderance of deep routes that the Raiders prefer, but JaMarcus Russell's 16.5 percent Underthrown Rate is pretty ridiculous. Following behind him in the "Just Didn't Get There" brigade are Eli Manning of the Giants (13.1), Tyler Thigpen of the Chiefs (13.1), Derek Anderson (12.9 -- How versatile of him - he can under- and over-throw!), and Hasselbeck again as well. No quarterback underthrew fewer receivers than Houston's Matt Schaub (4.9 percent), followed by Jason Campbell (6.4 percent), Jeff Garcia (5.8), Kurt Warner (6.9), and Drew Brees (7.3).

Finally, since we've been exposing the foibles of so many quarterbacks, it's time to take a shot at their receivers. As we mentioned, nobody had more dropped passes than Campbell, followed by Aaron Rodgers (38), Drew Brees (38 - imagine how efficient he would have been with half that many?), Peyton Manning (36), and Ben Roethlisberger (35).

More and more, we're understanding specific efficiencies and play responsibilities through the combination of advanced stats and film study. Expanding numbers as they pertain (and, perhaps, do NOT pertain) to quarterbacks is one of the most important aspects of football sabermetrics. The QB Rating metric was a handy-dandy shortcut (to what, we're not sure), but it's time to put away the abacus and opt for the exploded view of the game.

By Doug Farrar  |  September 16, 2009; 7:01 AM ET  | Category:  Doug Farrar , NFL , Quarterbacks , Statistics Save & Share:  Send E-mail   Facebook   Twitter   Digg   Yahoo Buzz   StumbleUpon   Technorati  
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