I took all quarterbacks who had a roughly average passer rating performance on at least 20 attempts (game rating of 75.0 to 85.0) in the last decade (2000-2009 seasons) and broke them down by the four categories used in the passer rating formula--completion percentage, yards per attempt, touchdown percentage and interception percentage. By focusing on roughly average performances overall as judged by the passer rating formula, we should be able to see how an extreme performance in one of the categories compares to another in points scored and team won-loss record. 645 quarterback games met the criteria and were included in the study.
Here are the correlations between the various categories and both total points scored and team win-loss record:
Completion Percentage and Points Scored: -0.08
Completion Percentage and Winning Percentage: -0.04
Yards Per Attempt and Points Scored: +0.21
Yards Per Attempt and Winning Percentage: +0.05
Touchdown Percentage and Points Scored: +0.32
Touchdown Percentage and Winning Percentage: +0.06
Interception Percentage and Points Scored: +0.27
Interception Percentage and Winning Percentage: +0.03
Total Number of Pass Attempts and Points Scored: -0.02
Total Number of Pass Attempts and Winning Percentage: -0.28
Let's put those into sentence form. Among quarterbacks judged to be roughly equal by passer rating . . .
Those with a better completion percentage score fewer points and win slightly less than those with a lower completion percentage.
Those with a better yards per attempt score more points and win slightly more than those with a lower yards per attempt.
Those with a better touchdown percentage score more points and win slightly more than those with a lower touchdown percentage.
Those with a better interception percentage score fewer points and win slightly more than those with a lower interception percentage.
Those with more total pass attempts score about the same number of points and win less than those with fewer pass attempts.
I added the total pass attempts thing to show one of the quirks of using the passer rating in individual game situations. I don't think we can fault a passer who has to throw alot because his team is trailing, and the chances of going through a game without an interception or completing a high percentage decrease as the sample size increases. I think we would all agree that throwing 50 passes without an interception is more difficult than throwing 20, yet both passers get the same sub-score for interception rate. The passers who avoided interceptions and got a perfect score by not throwing as much (25 passes or less) won 69% of the time in this group. In contrast, no passer among this group who threw 45 attempts or more without an interception, the more difficult feat, actually won the game (0-16-1).
A further breakdown of each category may be even more illuminating. Here are the points scored and winning percentage breakdowns by completion percentage:
|70 or higher||40||19.4||0.450|
Here we see that passers who are heavily dinged for completing a low percentage of passes score more points and win a higher percentage of games than other passers judged similar by passer rating. A quarterback completed less than 40% of passes only three times in this group of 645, and that quarterback's team won all three and they all scored at least 20 points. Each featured a yards per completion over 17.
Here is a breakdown by interception rates for this group:
|0.1 to 2.5||58||19.8||0.293|
|2.6 to 5.0||281||20.7||0.505|
|5.1 to 7.5||64||24.2||0.469|
|7.5 and up||18||24.3||0.500|
Here is the breakdown by Yards per Attempt:
|5 to 5.9||131||18.1||0.466|
|6 to 6.9||216||19.9||0.442|
|7 to 7.9||177||21.5||0.520|
|8 to 8.9||76||22.0||0.487|
And lastly, here is the breakdown by touchdown percentage:
|0.1 to 2.4||66||16.8||0.265|
|2.5 to 5.0||315||19.7||0.460|
|5.1 to 7.5||108||24.3||0.528|
|7.6 or up||37||24.5||0.595|
This entry was posted on Friday, February 26th, 2010 at 7:30 am and is filed under General, Statgeekery. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.