Above all other things, it is the responsibility of the quarterback to maximize the number of touchdowns scored and minimize the number of turnovers committed. The TD-INT ratio is a widely used metric, but interceptions don't tell the whole story. Football analysts need to stop ignoring the effect of quarterback fumbles on the effectiveness of an offense. An interception most of the time places the opposing team down the field, past the original line of scrimmage. Fumbles on the other hand tend to happen in the pocket or near the line of scrimmage, making them potentially far more damaging to the offense.

I propose the following formula:

Total fumbles are divided in half to account for the fact that, over a stretch of time, a team will recover roughly half of their fumbles. In addition, I've added the number of fumbles to the denominator to account for the fact that a fumble is not counted as a pass attempt like a touchdown or interception is. Although it is less useful on a single-game basis, the touchdown-turnover percentage (TD-TO%) provides a more complete analysis of a quarterback's value to his team over a longer stretch of time. In particular, it casts a very different view on Robert Griffin III (leading in AYP at the time the article was written), the player Barra highlights as the prime example for why AYP works.

I had the opportunity to see him live at the Redskins game against the Carolina Panthers. It was a rough game for the Redskins (they lost 21-13), and although there were many comments from fans during and after the game as to why their team has underperformed, one in particular stood out for me. About halfway through the third quarter, a young fan sitting near me asked his father, "When is the last time the Redskins scored a touchdown? They can't get the ball into the endzone!"

The key metric here, important for measuring Griffin's progress as a rookie, is that he is one of only four quarterbacks so far this year to average less than one passing touchdown per start: The others are Ryan Tannehill, John Skelton, and Cam Newton. Furthermore, Griffin has had an alarming tendency to put the ball on the ground this year, fumbling eight times (two lost) in nine games. Using my formula above, RG3's true TD-Turnover ratio is 8-7: His TD-TO% of 0.37% (Ranked 19th overall) is closer to that of Christian Ponder (0.17%) than Aaron Rodgers (5.95%).

This metric shows Griffin to be far from the upper echelon of the NFL, but I think most would say that's a fair assessment. Griffin is a talented rookie with a lot of room to grow and (unfortunately) a sub-par supporting cast. With an improvement of the Redskins team and a couple years of experience he could certainly be one of the top five quarterbacks in the league. However, as it stands now, Barra's metric fails the test provided by Robert Griffin III.