If you happened to hang on to your calculus book from college, now would be a good time to bring it back out, because it's time to test some of those old math skills.
When Don Smith was coming up with his formula, he decided that the best method was to award points based on how quarterbacks performed in relation to a solid standard. In other words, if a quarterback completed just half of the passes he threw, then he would get a point for hitting the average number. If he fell below 30 percent, then that quarterback would get no points, while passing above 70 percent would earn him two points. A similar system is then devised for the remaining three categories, with each quarterback given between zero and two points according to how well they do in each stat.
Now, because the high percentages are based on existing records, and we all know that records can be broken, the system allows for some wiggle room. That is why some quarterbacks will end up with a number greater than two for some of their stats.
The final step in the process is putting all the data together and coming up a number that makes sense. Once all the initial points are added up, they are divided by six. But the number you end up with after all that seems relatively tiny; for example, .983 doesn't look very impressive as an athlete's rating, so Smith decided to multiple it by 100. Therefore, a .983 rating is all of the sudden a 98.3, which looks much more substantial. Also, because of the wiggle room mentioned above, there is a chance that the greatest quarterbacks will end a season with a rating over 100. Check out the sidebar for a breakdown of Steve Young's amazing 1994 season in which he ended up with a rating of 112.8 [sources: NFL.com, Don Steinberg].
Now that we have our quarterback's rating, what comes next? Read on to find out the purpose behind the ratings.