Fantasy: QB Interception Rate Regression

| July 18, 2012

This off-season has been one of exponential growth for myself in terms of access to data (a PFF staple) and analyzing trends within that data. I looked at receivers and tight ends with a high yards-per-reception here and will look at quarterback interception rates from year-to-year in this article. When looking at touchdown rates, they are calculated based on the number of touchdowns per completion for quarterbacks. Keeping in line with the idea that a quarterback can only throw a touchdown on a completion, I used only a quarterback’s incompletions to calculate and analyze their interception rate.

In order to get a more significant sample size, I used ProFootballFocus.com data going back to 2008 and ProFootballReference.com as an additional resource to begin this study with the 2005 NFL season. For a quarterback to be included in this study, they require 400+ attempts in a season and 90+ attempts in their Y+1 campaign.

  • 136 quarterbacks qualified for study between 2005 and 2010.
  • The NFL average for this metric is 7.1% based on Y1 data.
  • 85 quarterbacks fell within the range of 5% and 9%, where there was little evidence of any trend for their Y+1 interception rate.

 

First, here are the 25 quarterbacks that were below the 5% threshold from 2005-2010:

 

Year Player INT Rate Y+1 Rate Change
2010 Tom Brady 2.38% 5.71% 3.33%
2007 David Garrard 2.56% 6.50% 3.94%
2008 Jason Campbell 3.14% 8.33% 5.19%
2010 Josh Freeman 3.28% 10.73% 7.45%
2010 Ben Roethlisberger 3.36% 7.41% 4.05%
2007 Jeff Garcia 3.39% 4.55% 1.16%
2009 Aaron Rodgers 3.66% 6.75% 3.09%
2006 Marc Bulger 3.67% 9.55% 5.88%
2010 Matt Cassel 3.72% 8.26% 4.54%
2007 Donovan McNabb 3.85% 4.87% 1.02%
2005 Jake Plummer 3.91% 9.15% 5.24%
2005 Bryron Leftwich 3.94% 6.67% 2.73%
2008 Kerry Collins 4.07% 8.25% 4.18%
2009 Brett Favre 4.17% 13.48% 9.31%
2010 Matt Ryan 4.21% 5.48% 1.27%
2010 Michael Vick 4.32% 8.24% 3.92%
2010 Kyle Orton 4.39% 8.82% 4.43%
2006 Donovan McNabb 4.41% 3.85% -0.57%
2009 Tony Romo 4.43% 10.77% 6.34%
2008 Chad Pennington 4.52% 8.70% 4.18%
2005 Kerry Collins 4.56% 12.50% 7.94%
2006 Peyton Manning 4.62% 7.87% 3.25%
2008 JaMarcus Russell 4.71% 8.73% 4.02%
2008 Donovan McNabb 4.87% 5.68% 0.81%
2009 David Garrard 4.95% 11.54% 6.59%

 

The first thing that sticks out is that one of these things is not like the other. That is Donovan McNabb in 2006. Of the 25 players, he was the ONLY one to repeat or lower his low interception rate the following season. In fact, 64% of them were above the NFL average the following season. During this six-year stretch even top names like Peyton Manning, Tom Brady, and Aaron Rodgers regressed and almost doubled their previous season’s rate. In short, a whopping 96% of these low interception rates rose the following season and by an average of over 4%.

 

Now, here are the 25 quarterbacks from 2005-2010 with an interception rate greater than 9%:

 

Year Player INT Rate Y+1 Rate Change
2006 Joey Harrington 9.09% 6.02% -3.08%
2006 Rex Grossman 9.17% 6.80% -2.38%
2007 Philip Rivers 9.20% 6.63% -2.57%
2005 Jake Delhomme 9.25% 6.55% -2.70%
2006 Chad Pennington 9.30% 11.11% 1.81%
2006 Matt Hasselbeck 9.32% 5.71% -3.60%
2010 Jay Cutler 9.36% 5.30% -4.06%
2010 Chad Henne 9.52% 8.33% -1.19%
2010 Matt Hasselbeck 9.55% 7.04% -2.51%
2007 Marc Bulger 9.55% 6.88% -2.67%
2007 Jon Kitna 9.71% 9.60% -0.11%
2006 Jon Kitna 9.82% 9.71% -0.11%
2007 Carson Palmer 9.90% 7.41% -2.49%
2007 Kurt Warner 10.00% 7.11% -2.89%
2007 Tony Romo 10.27% 8.00% -2.27%
2010 Drew Brees 10.48% 7.41% -3.07%
2006 Tony Romo 11.11% 10.27% -0.84%
2009 Matthew Stafford 11.36% 4.32% -7.04%
2009 Jay Cutler 11.87% 9.36% -2.51%
2009 Mark Sanchez 11.98% 5.70% -6.28%
2006 Ben Roethlisberger 12.17% 7.86% -4.31%
2008 Brett Favre 12.29% 4.17% -8.12%
2005 Brett Favre 12.34% 6.67% -5.67%
2010 Eli Manning 12.50% 6.96% -5.54%
2009 Jake Delhomme 12.59% 12.50% -0.09%

 

Not only is it eerie that there was the same sample size of 25 quarterbacks, but just like the low-rate group, 24 of the 25 saw an improvement in their rate the following season. Once again, a ridiculous 96% regressed towards the NFL average. The average quarterback saw a 3% reduction in their rate and 56% of them dropped down to the NFL average or below. Chad Pennington in 2006 was the only outlier to this trend, rising from 9.3% to an even higher 11.1% in 2007. In terms of looking for a sure thing in this world, the only things that beat this interception rate trend are death and taxes – and someone needs to check Donovan McNabb’s 2008 and Chad Pennington’s 2007 return!

Now, it is time for the important part: What quarterbacks are likely to increase or decline in 2012? Here are the names to remember this year:

 

2012 Winners

 

Year Player INT Rate
2011 Philip Rivers 9.26%
2011 Rex Grossman 10.36%
2011 Ryan Fitzpatrick 10.65%
2011 Josh Freeman 10.73%
2011 Carson Palmer 12.40%

 

Philip Rivers was obvious inclusion. He is a huge name in fantasy football that had a downright horrible first half of 2011. His interception rate was at or below the NFL average between 2008-2010, so he is a prime candidate to return to form in 2012 in this metric. As a likely backup, Rex Grossman probably will not see enough attempts in 2012 to be included in the 2013 study of this metric. Ryan Fitzpatrick had another season of 10%+ in 2009, which improved to 8.1% in 2010. While he will never be confused with a top NFL quarterback, Fitzpatrick is likely to move his interception rate closer to the NFL average in 2012. Josh Freeman has needed motion-sickness medication because of all the highs and lows with his interception rate in the NFL. His rookie year in 2009 saw a rookie-like 13.6%, which rebounded all the way to his ridiculous 2010 season of 3.3% to go along with 25 touchdowns. Then, 2011 happened. Tampa Bay literally fell apart before our eyes along with Freeman’s interception rate, which returned to a 2009-like 10.7%. This off-season brought about Freeman losing weight, a new coaching regime, and the added weapons of Vincent Jackson, Doug Martin, and Dallas Clark. Freeman is a prime candidate to see a 2012 interception rate closer to 2010, than his disappointing 2011.

 

2012 Losers

 

Year Player INT Rate
2011 Alex Smith 2.91%
2011 Sam Bradford 3.59%
2011 Aaron Rodgers 3.80%

 

Just three names qualify from 2011. Aaron Rodgers’ historic season should come as no surprise to fall into this category. Alex Smith was the ultimate game-manager in 2011 after seasons of 8.2% and 7.2% interception rates in San Francisco. His 7.3 aDOT is far below the NFL average and his 9.1% sack rate suggests he was more than willing to eat the ball and not risk a turnover. Sam Bradford’s interception rate is often overlooked from 2011. He attempted almost 36 passes a game on a team with few weapons around him. Bradford’s aDOT was a healthy 8.3 in 2011 and he improved his 6.3% interception rate from 2010 down to 3.8%.

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