Editor’s note: This is the third installment of a five-part series detailing the blueprint for winning the BCS national championship and measuring the Irish performance against this standard.

What is the defensive recipe for winning the BCS national championship? The aforementioned approach has been used to parse the data and identify the statistical metrics common to BCS champions. Staying consistent with the offensive results, these metrics have been divided into three categories (total, rushing and passing), and the data is presented in tabular form.

Each table includes the metric value (e.g. points allowed per game) and the corresponding national rank for the last 10 BCS champions. The last two rows indicate the established metric ranking and value cutoffs and the number of teams above (for ranking) and below (for value) these cutoffs.

The investigated metrics for each category are listed above each table and those found to be common and/or important characteristics of a BCS national championship caliber defense are italicized. Below each table is a brief discussion detailing pertinent characteristics and strong trends of the data. Where noted, data from all 20 BCS title game participants (winners and losers) has been incorporated.

The intent here is merely to present the results. The conclusions and implications of the data will be discussed in the fourth installment (Outlining the Blueprint).

Total

Metrics investigated:

• Third down efficiency
• Red zone efficiency
• Red zone touchdown efficiency
• Yards per play (YPP)
• Yards per game (YPG)
  
• Points per game (PPG)

Blueprint Total Defense Value And Ranking Data

[table id=228 /]

Third Down Efficiency

Similar to the offensive results, ranking data was not readily available for third down efficiency in 2000-2004 and the value of Oklahoma’s 2000 defensive unit could not be found.

But the available numbers show a strong trend. Of the five teams with available ranking data, all fall in the top 30 and two posted top 10 rankings. Additionally, seven teams held opposing offenses to a third down conversion rate of 33 percent or less, and none of the nine defensive units allowed more than a 35.6 percent third down conversion rate. As a group, the nine defenses allowed an average third down conversion rate of 31.3 percent. Including all 20 participants, 14 teams generated a third down efficiency of 35 percent or lower.

Yards Per Play (YPP)

Nine teams posted top 10 rankings as only the 2002 Buckeyes fell outside the top 10 and allowed more than 4.5 yards per play. The 10 squads averaged 4.3 YPP, a number that doesn’t change when the losing teams are also considered. Additionally, 16 of the 20 participants allowed 4.6 YPP or less and 15 ranked in the top 10.

Yards Per Game (YPG)

Similar to YPP, nine teams posted top 10 rankings in yards per game. Again, the 2002 Buckeyes fall outside the 10th-ranked cutoff value and are the only defense that allowed more than 303 YPG. On average, the 10 defenses allowed 277.9 YPG with Alabama’s 2009 squad leading the pack at just over 244 YPG, good for 2nd in the country. Including the losers, 17 teams allowed 303 or fewer YPG and ranked 13th or better in this category.

Points Per Game  (PPG)

Same story, third verse. One team—LSU in 2007—ranked outside the top 10 as nine teams posted rankings of 8th or better and allowed fewer than 16.5 PPG, and seven teams were under 13.6 PPG. The average per game point production of the 10 teams is just under two touchdowns per game (13.7 PPG). Using all 20 data points, 16 teams allowed 16.8 PPG or less and ranked in the top 12 in this metric.

Rushing

Metrics investigated:

• Yards per attempt (YPA)
• Yards per game (YPG)
  
• Touchdowns

Blueprint Rushing Defense Value And Ranking Data

[table id=230 /]

Yards Per Attempt (YPA)

Nine teams ranked 25th or better in yards per attempt and eight ranked 20th or better. The 10 teams allowed a paltry average of three YPA and an average ranking of 14.5 as nine teams held opposing rushers to 3.4 YPA or less. Including all 20 participants does not change the average as 19 teams allowed 3.8 YPA or less and 17 ranked in the top 30 in this category.

Yards Per Game (YPG)

The 10 teams allowed an average of 95.8 yards per game (average ranking of 13.7) in this category and include a 1st place ranking by the 2004 Trojans and a group-low 67 YPG by the 2003 Tigers. Additionally, eight teams allowed fewer than 110 YPG and ranked 23rd or better. Including the losing squads, 16 teams allowed fewer than 117 YPG and ranked 23rd or higher.

Touchdowns

Seven teams ranked in the top 10 in rushing touchdowns allowed, eight ranked in the top 25, and nine ranked in the top 30 including three first place finishes (2002 Buckeyes, 2003 Tigers, and 2009 Crimson Tide). As a group, the 10 teams allowed an average of 8.6 rushing touchdowns per year and a ranking of 12.3 as no team surrendered more than 15 touchdowns on the ground. Those on the losing side of the equation fared differently as only four losing squads allowed nine or fewer touchdowns and only three ranked in the top 10.

Passing

Metrics investigated:

• Yards per attempt (YPA)
• Yards per completion (YPC)
• Yards per game (YPG)
  
• Touchdowns
• Completion percentage
• Sacks
• Attempts/sack, normalized to account for differences in pass attempts
• Pass efficiency

Blueprint Passing Defense Value And Ranking Data

[table id=231 /]

Yards Per Attempt (YPA)

All but one team—Ohio State in 2002—ranked in the top 10 as nine squads posted rankings of 9th or better and allowed 5.7 yards per attempt or less. As a group, the last 10 BCS champions allowed an average of 5.5 YPA (average ranking of seven). Including the losing defensive units, 16 teams allowed 5.7 YPA or less and ranked 9th or better.

Yards Per Completion (YPC)

Eight teams posted a ranking of 27th or better and allowed 11.8 yards per completion or less as the 10 defenses surrendered an average of 11 YPC for an average ranking of 21.7. Additionally, six teams allowed fewer than 11 YPC and five ranked in the top 10 in this metric. Finally, 17 of the participants allowed 12 or fewer YPC and 15 ranked 27th or better.

Yards Per Game (YPG)

Only the 2002 Buckeyes performed poorly in this category, allowing over 240 YPG and ranking 95th in the country. As a group, the defenses allowed an average of 182 passing yards per game and a ranking of just under 24 as nine teams allowed fewer than 200 YPG and ranked 34th or better. The losing defensive units aren’t appreciably different averaging 183.8 YPG and a 32nd ranking as 17 of the 20 participants allowed fewer than 205 YPG and 15 ranked in the top 35.

Touchdowns

Eight teams ranked 16th or better allowing touchdowns through the air and nine performed well enough to garner at least a 27th place ranking including the 2001 Hurricanes who allowed only five passing scores. Nine teams also allowed 14 or fewer touchdowns and four units allowed 10 or fewer touchdowns. On average, the 10 teams allowed 11.5 touchdowns per year and ranked in the top 16. Adding the losing teams, 17 allowed 15 or fewer touchdowns and 16 ranked in the top 30 in this metric.

Completion Percentage

On average, the defenses allowed opposing passers to complete only about half of their passes, a level of performance good enough to generate an average ranking slightly better than 18. Nine of the championship teams allowed less than a 54 percent completion rate and ranked 19th or better and 17 of the 20 participants allowed less than 56 percent completion rate and ranked 33rd or better.

Pass Efficiency

Nine teams ranked in the top 10 with pass efficiency ratings of less than 102 as the 10 defenses averaged a pass efficiency of 94.6 and a ranking of 6.2—the highest average ranking value of any defensive category with the exception of points per game. The 2001 Hurricanes led the way once again, posting a gaudy, 1st place pass efficiency of 75.6. Including the losers, 16 teams generated pass efficiency ratings of 105 or better and ranked in the top 10.

Next up, summarizing the offensive and defensive results, conclusions, and defining the blueprint.