Total QBR (quarterback rating) is something we often look at and simply nod our heads in agreement without really knowing the full details of the statistic. The mathematical formula has transformed the way we view quarterbacks.
A number of factors are incorporated in determining total QBR, including win probability, expected points, dividing credit and clutch index. Each quarterback is rated on a scale from 1-100, with 50 being an average score.
Instead of providing the textbook descriptions for each of the factors that go into QBR, we'll just provide short summaries before we show you to the top-10 QBR leaders in the NFL.
Win Probability
This category incorporates down, distance, yard line, clock time, timeouts, home field, field surface, and score/outcome of the game. Each play by the quarterback is scored based on how much they contributed to the team's win. Win probability treats each victory the same, whether the outcome is a blowout or decided on a last-second field goal, but the other categories exist to balance that out.
Expected Points
Expected points is based on the idea that as a team moves closer to their opponents' end zone, they're actually gaining points even though they may not be scoring on that drive, otherwise known as "point potential." Clock time, home field, timeouts and field surface are other factors incorporated into this category. Say the drive ends deep in the opponents territory due to a missed FG or a fumble by another player; that will be taken into account.
Dividing Credit
Obviously the quarterback isn't responsible for everything. A five yard screen pass can turn into a 60-yard catch-and-run, and that's not entirely the quarterback's doing. This category factors in overthrows, underthrows, catches, yards after the catch, pass protection, dropped passes, defended passes, and more to see exactly how much the quarterback contributed to that play.
Clutch Index
This one is pretty obvious. The quarterback is rated based on how critical a certain play is based on when it happens in the game. For example, first-and-goal from the five-yard line in the first quarter during a tied game will get a completely different clutch index than first-and-goal from the five-yard line mid-way through the fourth quarter trailing by six points.
Hopefully that was clear enough for you to understand QBR and what it means. ESPN provides a complete analysis of the statistic, which you can read about here.
Here are your top-10 QBs in the NFL based on the QBR statistic:
1. Philip Rivers, SD - 84.8 Total QBR
2. Peyton Manning, DEN - 84.7 Total QBR
3. Aaron Rodgers, GB - 83.4 Total QBR
4. Eli Manning, NYG - 81 Total QBR
5. Tony Romo, DAL - 80.4 Total QBR
6. Andrew Luck, IND - 80.1 Total QBR
7. Mike Glennon, TB - 72.7 Total QBR
8. Brian Hoyer, CLE - 72.2 Total QBR
9. Matt Ryan, ATL - 70.5 Total QBR
10. Matthew Stafford - 69.7 Total QBR
