Aug 15

Examining Outliers of Relative Yards and Yards Allowed per Play

NFL Preview

Last year, when examining the standout play of the Seattle Seahawks defense and Denver Broncos offense, we discussed many factors that influenced their overall efficiency in the respective unit. However, we only examined the true details of regression facing outliers in Relative Offensive Passer Rating (as it related to Denver) and Relative Defensive Passer Rating (as it related to Seattle). In looking at that, we saw how often teams regressed when pushing the limits with “abnormally” elite play in the passing game.

We made this breakdown on a relative scale due to the constantly improving efficiency of the passing game in the NFL. For example, the league improved from a 86.02 passer rating to 88.8 last year, as mentioned in yesterday’s story. Go back even 20 years ago, when the league owned a 78.44 passer rating, and the change is obvious. A 1994 team with a triple-digit rating isn’t the same as a 2014 team with a triple-digit rating, at least when context is included. After all, the league has evolved to understand passing efficiency better, and we judge team and player efficiency relative to their peers. (We may critique that a player isn’t “good enough” to play in the NFL, but they’re all still great football players at the end of the day. It’s just not as good the standard established that said player’s peers.)

A similar dynamic applies for overall offensive efficiency. Last year, the league averaged 5.44 yards per play. This just shy of the 5.45-yard average in 2011, which tops the league in any season since the NFL-AFL merger. The 2014 average also marks a massive improvement from the 4.99-yard average in 1994. There are several reasons for this, with the explosion of the passing game being the primary one. It should follow that with more efficient passing, the league will have a higher yards per play average.

At the time when we analyzed the Seahawks and Broncos, we thought it was an improvement advancement in football analysis to look at relative statistics. The focus on those changes in passing efficiency were obvious. However, we failed to think then about the potential changes in per-play efficiency overall. Hence why we focus today’s study on the year-to-year progression of Relative Yards per Play and Relative Yards Allowed per Play, and its statistical outliers. And of course, with this being the 2015 NFL Preview and all, we look for the statistical outliers from 2014 that will lead to offensive or defensive efficiency regression in 2015.

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