The 2011 line did not feature a dominant nose tackle. As a predominantly one gap scheme, it did not necessarily need a great one. Terrence Cody was the starter and Haloti Ngata saw some snaps at the position.
At the three technique, Cory Redding was a big - and at the same time overlooked - part of the line's success. Often forgotten, Redding could provide inside pressure from base packages on early downs, something this current Ravens team does not have, apart from perhaps Timmy Jernigan. Jernigan, however is a superior player against the run, at times able to bench blockers of him, while Redding was strictly a one gap penetrator.
The 2015 defense will feature Brandon Williams, an elite nose tackle and a tremendous upgrade over Terrence Cody. The 2011 Ravens were generally stout against the run but there were a few outliers like the playoff game against the Texans and the road loss against Seattle. In both those games, one hundred yard rushers were allowed.
The Ravens have not allowed a hundred yard rusher since Williams has been drafted. That will be expected to continue.
At the five technique, no one on the current roster comes remotely close to Haloti Ngata in his prime. With the loss of Brent Urban, pass rush productivity could be an issue as Chris Canty ranked dead last in that very category, per Pro Football Focus. Carl Davis could be an important piece, as he demonstrated pass rush prowess at the senior bowl and throughout his college career, being noticeably effective on stunts.
Where I think the 2015 defense has a clear advantage is in the depth department. Kapron Lewis-Moore, Lawrence Guy and DeAngelo Tyson have the edge over Brandon McKinney and the second year version of Arthur Jones. If Brent Urban can return down the stretch, the depth will be as good as can be.