Sports Illustrated's Peter King explained ESPN's newest stat, called "Total Quarterback Rating," on Monday. The system measures "the quarterback's contribution to the result on every play except handoffs" and is on a scale of 1-100. For the simple fact that a perfect score is 100 and not 158.3 already makes it better than quarterback rating.
Some of the differences include factoring yards after catch into the equation, considering some plays that are made in crucial moments of games and counting lost fumbles and sacks taken as well.
The system was developed by ESPN employees in the production analytics department as well as Trent Dilfer (among other quarterback minds). They watched every single NFL game since 2008 to collect the data, and the network will explain the new stat in detail on Friday night.
