Over the past two days we've looked at how the 2011 National Champion Crimson Tide's defense has matched up historically against other programs and past Alabama squads. Today we'll did a little deeper into the details of what this year's squad was able to accomplish by breaking down what opposing offenses couldn't.

To start, this chart shows the offensive yardage Alabama's opponents have accrued against the Crimson Tide defense over the past five years. The white numbers indicate the total number of touchdowns in that category.

Alabama Opponents Offensive Production 2007-2010

Source: CFB Stats

Basically, this year's defense wasn't just simply the best of the Nick Saban era, it was better by a huge margin. The number of touchdowns was halved from 2010 season and the 2,387 yards allowed was more than 30% better than the 2009 squad who, you might recall, were also good enough to garner a crystal football.

To break this down a bit further I drew up a graphic that showed the offensive yards-per-play production of every Alabama opponent in 2011 juxtaposed with their season average against all other opponents (data is after the jump).

Alabama Opponents Offensive Production per Play

Source: RollTide.com

Over the course of the season, Alabama's defense allowed an average of just 3.3 yards per play -- a full two yards less than the season average of all opponents (5.3 ypp). In fact, the only team to exceed their season average against Alabama was Georgia Southern. That outcome is skewed partly due to the relatively low number of plays the Eagles were able to run against the Crimson Tide (46). The only teams to manage fewer offensive plays against Alabama last year were Vanderbilt (43) and LSU in the BCS National Championship game (44).

LSU's offensive performance in New Orleans set another other low water mark as well. The Tiger's 92 yards of total offense in the BCS National Championship game was only two yards better than Kent State was able to manage in the Crimson Tide season opener. To find an SEC foe who managed less than LSU's offense on Jan. 9 you would have to go back all the way to 1980 when the Crimson Tide defense simply smothered Tennessee in Neyland Stadium. The Volunteers only managed 59 yards of total offense on that rainy afternoon three decades ago.

Now Coach Saban's defense isn't so much designed to limit yards as it is geared to stop offensive production. In that respect the point to to deny opponents third down conversions and, by extension, opportunities to score. To examine that, I've charted the conversion rates of every Alabama opponent in 2011 (actual numbers are at the bottom of this post).

Alabama Opponents Third Down Conversion Rates

Source: RollTide.com

The standard Coach Saban sets for the defense is a 70% efficiency on third downs. The Crimson Tide fell below that mark just one time in 2011, allowing Penn State to convert on 8 of 17 third down attempts for a 47% success rate. Obviously, the result of this should be reflected in a decrease in corresponding first downs by Alabama's opponents.

Here are the first down totals for the Crimson Tide's foes over the past half-decade.

Alabama Opponents First Downs 2007-2011

Source: CFB Stats

As we expected, teams found moving the chains against Alabama in 2011 was a rather difficult feat even given the stingy standard of Coach Saban's past Alabama squads.

Finally, the whole point of all these efforts is to keep opponents from scoring. Each individual component we've looked at above has illustrated one aspect of Alabama's ability to impede other team's offensive progress. None of that matters if they still find ways to put points on the board. Obviously, opposing teams have the ability to score using their defense and special teams, but sufficiently impeding their offense from controlling the game limits even those opportunities.

This chart looks at the average points per game each of Alabama's opponents scored over the course of the season against all other opponents against what they were able to manage against the Crimson Tide (raw numbers below).

Alabama Opponents Points Per Game 2011

Source: CFB Stats

NOTE: The opponent season average expresses each team's 2011 total minus their numbers against Alabama.

NOTE: The opponent season average expresses each team's 2011 total minus their numbers against Alabama.