Friday, January 29, 2010

Reevaluating Quarterback Rating as a Performance Tool

In football the quarterback rating statistic has always been a quirky point of emphasis. It is one of the chief indicators that pundits use to evaluate the performance of a quarterback in a given situation be it when blitzed, in the 2 minute drill, on the first drive of the game, etc. However, despite all this attention paid to the quarterback rating, it can be argued that the interpretation of the statistic itself is in error. Most view the meaning behind the quarterback rating as ‘the efficiency of a quarterback’. Although useful, a better statistic would be to evaluate the influence of the quarterback in relation to that efficiency instead of focusing on efficiency alone. Quarterback rating should judge the prolific nature of the quarterback if it is to be an effective quantitative tool in quarterback performance measure.

The formula used to compute quarterback rating (shown below) was developed by Pro Football Hall of Fame executive Don Smith in 1971.

The equation breaks down into 4 separate components: first, completion percentage where 50% was used as the average benchmark. That is an average quarterback performance involved completing 50%. From that base point poor and high quality performance points were established at 30% and 70% respectively. The second part involves yards per attempt with an average performance being 7, poor being 4 and high quality being 11. The third and fourth parts focus on touchdown passes per attempt ratio with an average performance being 5% and interception per attempt ratio with an average performance being 5.5%. Overall an average performance netted 1 point whereas poor and high quality performances netted 0 and 2 points respectively. Finally the 100 divided by 6 element was based on an average performance netting a 66.7% out of 100% grade scale. Note that 2.375 is the highest total allowable for any of the components.

The problem with the above methodology as it relates to what should be the goal of the quarterback rating is that the efficiency measure is phantom exponentially extended. Basically the methodology projects a performance ad infinitum based on the current statistics. It is due to this inherent application why Quarterback A can complete 8 of out 10 passes for 168 yards with 2 touchdowns and 0 interceptions (statistically perfect rating 158.3) and have a better rating than Quarterback B who completes 32 out of 41 passes for 410 yards and 4 touchdowns and 1 interception (130.7). Quarterback A had a more efficient performance than Quarterback B, but which quarterback was more instrumental in the offense of their particular team? Clearly Quarterback B, but the quarterback rating does not accurately reflect that reality.

Therefore, if quarterback ratings are going to continue to be used as quantitative measurement tools in quarterback evaluation, a cap needs to be assigned to curtail the inherent exponential proficiency estimation. The best means to determine influence would be relate the cap back to yardage. The following criterion or something similar would be suitable:

Yards = Maximum Quarterback Rating Possible

0-199 = 99.9
200-249 = 119.9
250-299 = 139.9
300+ = 158.3

With the application of these caps the overall formula for calculating quarterback rating would not change, but if a quarterback failed to throw for more than 249 yards it would not matter if the formula calculated a rating of 146.7 because officially the rating would be reduced to 119.9. Moving quarterback rating beyond simple efficiency and adding game influence increases its statistical power and the ability to accurately differentiate between high quality and quarterbacks that are only asked to do so much to aid their offense, which is supposed to the real point behind quarterback rating in the first place.

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