Welcome to the Advanced Stat of the Week column. Each week, I will explain an advanced (or semi-advanced) stat and illustrating how understanding it can affect your knowledge of each team in the division.
This week's stat is Net Yards per Attempt (NY/A).
Net yards per attempt is a derivative of the grandfather of all passing stats: Yards Per Attempt (YPA). YPA may be the single most telling stat in football. If you want to know why teams win and lose, first look at their YPA. Passing yards are wholly irrelevant to winning football games, but YPA goes a long way to determining the outcome.
Like its stately cousin, NY/A helps us understand what happens each time the quarterback drops back for a pass. NY/A is calculated by subtracting sack yardage from passing yardage, then dividing by passes attempted plus sacks. In other words:
(yards passing - sack yards) / (pass attempts + sacks) = Net Yards per Attempt
Backup quarterbacks are always popular, and for a brief moment in 2011, it appeared T.J. Yates would be named mayor of Houston. The Texans won his first few games after Matt Schaub went down with injury, and it appeared that he was the perfect backup plan. After a late-season swoon, he even won a playoff game, leading many fans to question just how important Schaub really was.
The answer: VERY.
A quick look at NY/A tells the whole story:
Yates had a very respectable YPA, but that doesn't take into account his horrible sack rate. Yates went down nearly twice as often as Schaub, racking up almost the same number of sacks in half the attempts.
Schaub's YPA was gaudy, but what hurt the Texans was the almost two full yards per attempt difference between playing with Yates and playing with Schaub. It's important to recognize as well that two of Yates' starts came against the Panthers and Colts, who had horrible pass defenses.
Yates was a great story, and the Texans' play after Schaub went down was inspiring, but there is a reason that they couldn't get past the Ravens.
On defense, we can see the real impact of this number. The Texans were second in the NFL in NY/A, behind only the Steelers. Each time an opposing quarterback dropped back, he could only expect an average of 5.2 yards per drop-back. That makes even 3rd-and-medium situations tenuous at best for offenses.
Again, pressure is the key here. The Texans led the league in opponents completion percentage and were sixth in sacks. When you combine good coverage and pressure, the result is a championship defense. In the playoffs, the Texans' defense posted nine sacks in two games, and kept right on their regular season pace allowing just 5.3 NY/A.
It was the Texans' ability to maintain consistent pressure on the quarterback even after the loss of Mario Williams that informs their decision to let him walk in free agency. While they couldn't replicate him with any one player, they were able to replace his performance in aggregate (for the Moneyball fans among you). Connor Barwin and Brooks Reed picked up 15.5 sacks after Williams went down, after combining for just two in the first five games of the year.