Romo’s QBR has dipped from 71.4 last season to 56.4. Vick’s has dropped from 64.4 to 53.3.
But Rivers, who faces the Kansas City Chiefs tonight, has taken the biggest plunge, going from a 62.7 in 2011 to 36.7 in 2012.
Let’s take a closer look at the biggest reason for his drop-off, as well as those of Romo and Vick.
Philip Rivers: No Vincent Jackson
Rivers’ average pass has traveled 7.3 yards downfield this season, tied for fourth-lowest in the NFL.
This season, Rivers is throwing downfield less, and has connected on only 4-of-16 attempts of more than 10 yards downfield to Jackson’s replacement, Robert Meachem.
Rivers has also struggled when under heavy pressure this season, though his issues aren't as great as the quarterback of the Dallas Cowboys.
Tony Romo: Bad decisions
He has twice as many interceptions (6) when under duress this season than he did the previous three seasons combined. (Duress is defined as being forced to move or alter a throw due to pressure.)
Romo has chosen to force throws in those situations, rather than throw the ball away. This season, Romo has thrown the ball away at a rate of about one of every 16 pass attempts when under duress. That's the fourth-lowest rate in the NFL. (For comparative purposes, the average quarterback throws the ball away about once every six attempts.)
Michael Vick: Confined to the pocket
Vick has been sacked or put under duress on one-third of his dropbacks this season, the highest rate in the NFL. He's also completed just 28 percent of his attempts when under duress which is the fourth lowest completion percentage in those situations.
When Vick has broken the pocket, the most common outcome has been for him to throw the ball away. He has more throwaways (9) than completions (7) when passing outside the pocket this season.