Passer rating is the name of the method for evaluating the performance of quarterbacks officially used by the National Football League. The Passer Rating is calculated using each quarterback's completion percentage, passing yardage, touchdowns and interceptions . The current "passer rating" or "quarterback rating" system (the former term being the official one) was conceived by Pro Football Hall of Fame's Don Smith in 1973; it was then applied retroactively to all previous seasons. The best passer rating that a quarterback can obtain under it is 158.3 (technically 158.333→), while the worst is zero. Conceptually, the average rating would be 79.2 (techincally 79.166→), since this is equidistant between zero and 158.3. The cumulative leaguewide average passer rating for the years 2000 through 2003, all inclusive, was 78.9 (the figure is typically rounded to the nearest 1/10 of a point); however in 2004 the league average was 82.8, the highest ever recorded.
Calculation
The passer rating is determined by four statistics, each of which are computed as a number between zero and 2.375. The benchmarks for these statistics are based on historical averages. If any of the components are less than zero, they are reckoned as zero; if any are over 2.375, they are reckoned as 2.375.  The completion percentage rating is calculated as
 The rating for average yards per attempt is calculated as
 The rating for touchdowns per attempt is calculated as
 The rating for interceptions per attempt is calculated as
The result is then summed, divided by 6, and multipled by 100. Since each of these numbers is at most 2.375, the maximum passer rating is . Criticisms The Passer Rating System has many critics, who have objected to it on several different grounds. The most frequentlyvoiced objection is that plays on which the quarterback is sacked to do not count toward compiling the rating; this actually gives a quarterback an incentive to deliberately take a sack rather than throw the ball away and have an incomplete pass devalue both his completion percentage and his yards per attempt. Another criticism is the fact that rushing yards gained by a quarterback do not result in his getting a higher rating — a particularly important contemporary issue due to the recent emergence of many excellent running quarterbacks in the NFL, most notably Steve Young, Daunte Culpepper, Donovan McNabb and Michael Vick. Some observers have proposed replacing yards per attempt with yards per play as one of the rating's components, counting both sacks and rushing attempts (in addition to passes actually thrown) as plays, thereby resolving both of the above issues. A third complaint concerns the placing of artificial limits (both upper and lower) on the points that can be earned in the various categories. Critics claim, for example, that it is unfair not to give a quarterback a higher rating for completing 90% of his passes than for completing 77.5%, or for averaging, say, 15 yards per attempt as opposed to only 12.5 (the limit of 2.375 applying in each instance) — although this is likely to affect only the rating for a single game and not for an entire season.
External Links and References  NFL.com QB Rating Page (http://www.nfl.com/news/981202qbrate.html)
 New York Times  The N.F.L.'s Passer Rating, Arcane and Misunderstood  January 14, 2004
