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By the Numbers: 2014 Defensive Performance - Part 2 in a Series

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Who was the Most Efficient and Consistent Defense in 2014?

Robert Hanashiro-USA TODAY Sports

In Part 1, the discussion focused on the defensive balance between the Top 10, Middle 10, and Bottom 10 teams. With that preliminary out of the way, this section we are taking a look into efficiency, consistency, and overall performance.>/p>

First, a little clarification; it was brought up in Part 1 that there seemed to be some correlation between the three groups’ time of possession. After digging deeper, there really is no significant correlation to being on defense less than your opponent and performance. There are three main categories a lower TOP falls into:

1. Ball Control – There are teams such as Georgia Tech, Arkansas, and even a Michigan State who either want to control the ball more or are run oriented which, by default, will burn the clock more.

2. Quick Strike Offenses – This is the flipside of ball control. Teams like Baylor, Texas Tech, and WKU are all excellent offensive teams, but their lack of ball control leaves their defense on the field. These teams rank 87, 117, and 110, respectively in TOP.

3. Inefficient Defense – Some teams such as Cal, Colorado, and Wyoming look excellent in terms of TOP, but they simply cannot stop their opponents and are prone to big plays. TOP is a result of allowing the teams to score far too quickly and often.

More than likely any team will have some combination of these factors. With that, we will say TOP is a result of scheme and / or execution.

To continue, the analysis in his part will break down efficiency and consistency using the following factors: Yards per drive allowed versus expected, Points per drive allowed versus expected, opponents scoring rate (% of drives resulting in scores), and the team’s defensive turnover rate. From that we have a simple power ranking of overall defense that is adjusted for strength of schedule. The efficiency and consistency components are not adjusted for strength of schedule; for clarity purposes, the overall defensive rankings will be shown as both unadjusted and adjusted. (Note: this is not a predictor of how teams will come into this year, simply a review of last season’s performances.)

What follows is an explanation of each component and the Top 25 Defenses in each category.

EFFICIENCY FACTORS

Yards Allowed

The concept of yards allowed per play is nothing new. This analysis looks at it a bit differently; for every possession, there is an expected number of yards to be gained. This analysis looked at expected yardage (based on opponent starting field position) and compared it to actual yardage allowed for each drive. Garbage possessions were eliminated, and only FBS opponents utilized.

Points Allowed

As with Yards Allowed, this is simply the number of points allowed, on a per drive basis, compared to the expected points allowed to determine a team’s efficiency.

Below the Top 25 for each are shown side by side for comparative purposes.

EFFICIENCY TOP 25 (Yards and Points Allowed)

CONSISTENCY

Opponent Score Rate – This is simply using the number of drives that an opponent scores either a field goal or touchdown versus the total number of drives. (Expressed as a percentage)

Turnover Rate – This is the number of defensive possessions (expressed as a percentage) that resulted in a fumble recovery, interception, or safety versus the total number of possessions.

The Top 25 are shown side by side to compare.

Consistency Top 25 (Opponent Scoring Rate and Turnover Rate)

Putting it Together

To develop the power rating, each of the components were synthesized then normalized. The strength of schedule was part of this as well. As stated earlier, for continuity purposes, the Top 25 will be shown both adjusted and unadjusted.

This is one of the foundation components that are used in predicting games. For the ratings we do, this is, for all intents and purposes, the way we derive one third of our defensive ratings. The next in our series will break down and rank the defensive units returning for the 2015/16 season.

For more statistics please visit: www.steelcard.blogspot.com

A big thanks to the following sites for their insights and information: www.ncaa.org , www.fbsdrivestats.com , www.footballoutsiders.com , and www.cfbstats.com