I think if any fan watched the Ducks this year, it was pretty apparent that the defense was not the same as we've seen in the last couple of seasons.
Oregon allowed teams to convert on third down 40.85% of the time (77th nationally and 11th in the Pac 12). Books could be written on that stat alone. That is the highest percentage for the Ducks going back to before 2007. The Ducks only got 5.25 Tackles for a Loss per game, putting them 95th nationally and last in the Pac 12. Again, their lowest number since before 2007. Sacks came in at 2.15 and Oregon only had one year (injury plagued 2012) that was lower for the Ducks. And all of these stats were accumulated on a per game basis that saw the Ducks once again facing the most number of plays of anyone in the conference and second most nationally.
I don't need advanced statistics or per play weightings to tell me that is abysmal.
As any fan might be thinking right now, who's to blame? First of all let's talk a little bit about the scheme that is employed by the Ducks. They use a hybrid 3-4 defense where an outside linebacker switches between a 3-4 and 4-3 front. Aliotti went to this system in 2009 as to complement Oregon's more up-tempo offense. If you're able to get teams in favorable yardage situations (2nd or 3rd and long) you can try and confuse the offensive line by bringing a variety of linebackers or lineman on blitzes, zone blitzes, and stunts to get off the field.
So the first thing this defense is going to try and accomplish is to get teams in long yardage situations. We already mentioned how poorly this team looked this year in Tackles for a Loss, but let's look at how it compares to previous seasons by each unit of the defense:
TFL/GM by Defensive Units
What is interesting to note, is that the defensive line has never been a large part of creating those long yardage situations. Since 2009, when Oregon implemented this new system, 2013 ranks right in the middle for the defensive backs (DB) and the defensive line (DL). But look at how terrible the linebackers were in relationship to previous seasons.
If Oregon isn't able to get teams in long yardage situations, obviously, its variety of play calls and attacking style is going to be muted. For example, an offense has a lot more of its playbook and the defense a lot less on 3rd and 4 than on 3rd and 7. I suspect this has a lot to do with why Oregon's 3rd Down Conversion percentages were as terrible as they were.
Finally, to better understand why this defense struggled so much I wanted to look at who was making the tackles.
Tackle Percentage by Defensive Units
There have been a lot of comparisons of this season to 2009. Brand new head coach has a 10-2 season. New defensive line coach, wide receiver coach, and offensive coordinator. Lost a game getting completely out-played (Boise State and Arizona). Key conference loss to Stanford on the road.
The tackling stats look very similar to 2009 as well.
The linebackers once again led the team in tackles, but at the second lowest rate while facing the second most number of plays per game. The defensive backs had their second highest tackle percentage, but faced the least number of passes by percentage of plays. And again the defensive line had a middle of the pack performance.
So what do think is happening when teams are running the ball against us more than they have in the past, our DBs are making a lot more tackles, and we're not getting teams in long yardage situations as often as we have in the past?
You get a season very similar to 2009.