Quarterback Ratings: How Does it Work?
Source: 2004 National Football League
Record & Fact Book
The QB Rating has become the
standard benchmark for gauging the success
of QBs, despite the era in which they
played or what kind of offenses they ran.
I've always been curious how the rating is
determined, especially since it always
seemed weird that a perfect rating is
158.33. Why isn't is a baseten system
where 100 is the perfect score?
A visit to the NFL.com history section
provided the following answers:
The NFL
rates its passers for statistical
purposes against a fixed performance
standard based on statistical
achievements of all qualified pro
passers since 1960. The current system
replaced one that rated passers in
relation to their position in a total
group based on various criteria. The
current system, which was adopted in
1973, removes inequities that existed in
the former method and, at the same time,
provides a means of comparing passing
performances from one season to the
next.
It is important to remember that the
system is used to rate passers, not
quarterbacks. Statistics do not reflect
leadership, playcalling, and other
intangible factors that go into making a
successful professional quarterback.
Four categories are used as a basis for
compiling a rating:
Percentage of completions per attempt
Average yards gained per attempt
Percentage of touchdown passes per
attempt
Percentage of interceptions per attempt
The average standard is 1.000. The
bottom is .000. To earn a 2.000 rating,
a passer must perform at exceptional
levels, i.e., 70 percent in completions,
10 percent in touchdowns, 1.5 percent in
interceptions, and 11 yards average gain
per pass attempt. The maximum a passer
can receive in any category is 2.375.
For example, to gain a 2.375 in
completion percentage, a passer would
have to complete 77.5 percent of his
passes. The NFL record is 70.55 by Ken
Anderson (Cincinnati, 1982). To earn a
2.375 in percentage of touchdowns, a
passer would have to achieve a
percentage of 11.9. The record is 13.9
by Sid Luckman (Chicago, 1943). To gain
2.375 in percentage of interceptions, a
passer would have to go the entire
season without an interception. The
2.375 figure in average yards is 12.50,
compared with the NFL record of 11.17 by
Tommy O'Connell (Cleveland, 1957).
In order to make the rating more
understandable, the point rating is then
converted into a scale of 100, with
158.3 being the highest rating a passer
can achieve. In cases where statistical
performance has been superior, it is
possible for a passer to surpass a 100
rating. For example, take Steve Young's
recordsetting season in 1994 when he
completed 324 of 461 passes for 3,969
yards, 35 touchdowns, and 10
interceptions.
The four calculations would be:
Percentage of Completions
324 of 461 is 70.28 percent.
Subtract 30 from the completion
percentage (40.28) and multiply the
result by 0.05. The result is a point
rating of 2.014.
Note: If the result is less than zero
(Comp. Pct. less than 30.0), award zero
points. If the results are greater than
2.375 (Comp. Pct. greater than 77.5),
award 2.375.
Average Yards Gained Per Attempt
3,969 yards divided by 461 attempts
is 8.61. Subtract three yards from
yardsperattempt (5.61) and multiply
the result by 0.25. The result is 1.403.
Note: If the result is less than zero
(yards per attempt less than 3.0), award
zero points. If the result is greater
than 2.375 (yards per attempt greater
than 12.5), award 2.375 points.
Percentage of Touchdown Passes
35 touchdowns in 461 attempts is
7.59 percent. Multiply the touchdown
percentage by 0.2. The result is 1.518.
Note: If the result is greater than
2.375 (touchdown percentage greater than
11.875), award 2.375.
Percentage of Interceptions
10 interceptions in 461 attempts is
2.17 percent. Multiply the interception
percentage by 0.25 (0.542) and subtract
the number from 2.375. The result is
1.833.
Note: If the result is less than zero
(interception percentage greater than
9.5), award zero points.
The sum of the four steps is (2.014 +
1.403 + 1.518 + 1.833) 6.768. The sum is
then divided by six (1.128) and
multiplied by 100. In this case, the
result is 112.8. This same formula can
be used to determine a passer rating for
any player who attempts at least one
pass.
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