QBR: Closer look at NFC West quarterbacks

August, 4, 2011
8/04/11
2:17
PM ET
Total Quarterback Rating (QBR) should affirm what we know most of the time while occasionally challenging what we think.

The newly developed metric would have no value if it tried to convince us Derek Anderson was better than Tom Brady (it does not do this). If it told us Chad Pennington was better in 2008 than Peyton Manning was in 2010 -- it does make that case -- we should at some point revisit those specific seasons for those specific quarterbacks. I've been most interested in learning what QBR reveals about performances relative to the passer-rating formula in use since 1973.

For example, Matt Hasselbeck finished with similar passer ratings in 2009 and 2010, but QBR favored his 2010 season by a wide margin. Something about Hasselbeck's 2009 season did not sit well with the QBR formula. Even his 2008 season, complete with a career-low 57.8 passer rating, held up better. Why was this?

Alok Pattani from our analytics team pointed to a couple of factors:
  • Hasselbeck made greater contributions as a runner in 2008 than in 2009.
  • Hasselbeck fumbled only once in 259 plays during the 2008 season. Seattle recovered. He fumbled 18 times in 1,139 plays during the 2009 and 2010 seasons. Seattle lost eight of those 18 fumbles. That would have helped 2008 make up ground.

There were other factors, but those two were prominent. Separately, Hasselbeck's production on third down improved steadily since 2008. His third-down completion percentage rose from 36.7 in 2008, to 53.6 in 2009 and 60.9 last season. His sacks per pass play also steadily declined on third down.

I was also curious why Hasselbeck's QBR for 2010 doubled the 2008 QBR for then-San Francisco 49ers quarterback J.T. O'Sullivan, even though their passer ratings were similar. One key: O'Sullivan wasn't nearly as good on third-down pass plays across categories that included completion percentage, touchdowns, interceptions, sack percentage and conversion rate.

Understanding such disparities requires understanding QBR. Once QBR becomes established, considering the computations will not be relevant for those merely interested in the bottom line. We'll simply need to know that a season-long QBR around 50 would be near average, while a season-long QBR in the 65 range would reflect Pro Bowl-caliber play. Players will rarely reach an 80 QBR for a season, and it's impossible to reach 100 because a quarterback could, in theory, always complete one more pass for one more yard, etc.

ESPN plans to unveil details more fully during a "SportsCenter" special Friday night at 8 p.m. ET. A news release promoting the new metric offers the following details regarding QBR:
  • Total QBR measures all of the significant contributions by a quarterback during the course of a game and accounts for precisely how much he impacts his team’s performance and chances of winning.
  • Total QBR is based on all of a quarterback’s plays (rushing, passing, sacks, fumbles, interceptions, penalties, etc.), and it calculates the per-play net impact of the quarterback on the ability to score. Each play is weighted by the situation (i.e., down and distance, field position, time during the game) and its importance to the game’s outcome.
  • Another variable, division of credit, assigns a percentage to how much credit a quarterback should get for a positive play -- or blame for a negative play. ESPN analyst Trent Dilfer helped come up with additional data to consider, including how far a pass travels in the air, where the ball was thrown on the field, yards after catch, whether the quarterback faced pressure, etc.
  • QBR draws from 60,000 plays over the past three years to assign credit or blame for every play involving the quarterback. It measures quarterbacks on a 100-point scale, whereas the NFL's passer rating formula maxes out at 158.3.

According to those standards, Kurt Warner is the only NFC West quarterback since 2008 to post a Pro Bowl-caliber season.

And now, on to the chart showing passer rating and QBR figures for NFC West quarterbacks since 2008.

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