The Ravens have had a top-ten scoring defense every season since 1999, save one. That's 11 of the last 12 seasons in the top ten, and seven of 12 in the top five.
During that 12-year stretch, Marvin Lewis, Mike Nolan, Rex Ryan, Greg Mattison and Chuck Pagano have all served as Ravens defensive coordinator. The Ravens have run several different defensive systems, based out of alignments including the 3-4, 4-3 and even 46.
The one constant throughout has been 13-time Pro Bowl linebacker Ray Lewis.
37-year-old linebacker Ray Lewis.
In 2012, the Ravens haven't been bad statistically. They're allowing 17.8 points per game, seventh-best in the NFL. But they haven't looked like the dominant, suffocating and punishing unit that they used to be.
So what's wrong? If the Ravens defense has consistently been The Ravens Defense regardless of coach or scheme, it's got to be the players. If it's the players, could it be that stalwarts like Lewis and Ed Reed are finally too old to play like they used to? Or are the newcomers just not pulling their weight?
To answer that, we'll need to look at what's made the Ravens so successful over the years.
A Dozen Years of Dominance
This table shows the Ravens defensive stats for the last 12 seasons, with stats pulled from Pro Football Reference. From left to right, the table has the Ravens' points allowed per game, average net yards per attempt allowed, average yards per carry allowed and their rank in the NFL that year for each.
The Ravens' run defense has been consistently amazing. They've finished in the top ten in average yards per carry for each of the past 12 years, no exceptions. From Tony Siragusa to Haloti Ngata, the Ravens big uglies have always controlled the line of scrimmage. Behind them, Lewis has always been there to clean up.
2007 sticks out like a sore thumb. The vaunted Ravens D ranked just 22nd in the NFL in scoring defense.
The Ravens were the best run-stuffers in the NFL that year, so it didn't have anything to do with opposing running games. No, the problem was the 6.8 average net yards per attempt they were allowing through the air. During their 12-year run, the Ravens never allowed teams to be so effective passing the ball as in 2007, and their scoring defense was never as soft.
Until this year.
Pass Defense Falling Apart?
After five games, the Ravens are allowing an average 7.0 net yards per attempt. Their pass defense hasn't been this porous since 1996, when they allowed the same net yards per attempt along with 27.6 points a game. The '96 squad had the fifth-worst scoring defense in the NFL.
That team also went 4-12.
To find out what's wrong with the pass defense, let's examine Pro Football Focus grades. PFF analysts watch every player on every play and grade their performance. The grades aren't perfect, but they do a great job of illustrating who's playing well and who's playing poorly.
From 2008 to 2011, the Ravens finished second, first, fifth and second in overall defensive grades. Unsurprisingly, they graded out amazingly well against the run—first, first, fifth and second in that span. At the moment, PFF grades their run defense seventh.
Their pass rush, though, has been a different story; the Ravens were an awful 25th, 29th and 26th from 2008-2010. Clearly, the great Ravens defenses of the past few seasons weren't relying on pressuring the quarterback. In 2012 so far, they're back to their usually lackadaisical pressure; the Ravens are ranked 27th in PFF pass-rush grades.
But pass coverage is a different story. Over the last four seasons, the Ravens have graded out second, first, first and first in the NFL in pass coverage. They've blanketed opposing receivers, taking away options downfield and limiting their opponents to ineffective ankle-biting.
So far in 2012, the Ravens pass coverage is ranked 23rd.
Breaking Down the Breakdowns
On the very first play of the Ravens game against the Philadelphia Eagles, the Eagles attacked the soft underbelly of the Ravens pass coverage:
The Ravens line up in their base 3-4, while the Eagles are in a single-back formation. There are two pairs of receiving targets, one on either side of the center. Tight ends Brent Celek and Clay Harbor are on the bottom (offense's left), and two receivers are lined up in a stack at the top (offense's right):
The right outside receiver runs a fly route, while the right slot receiver runs down the seam. Celek runs a deep in, and Harbor stays in to block. Right off the bat, the Ravens blow the coverage:
Strong safety Bernard Pollard had snuck up to show tight man coverage on the slot receiver, Jeremy Maclin, while cornerback Lardarius Webb was eight yards deep off the outside wideout. At the snap, Pollard actually turns to cover the outside wideout, leaving the slot man to run the seam route uncovered.
Lewis, circled in red, allows Maclin to fly by without notice. Clearly, that receiver is not his responsibility. However, with Pollard double-covering the outside man, and fellow inside linebacker Jameel McClain blitzing, Lewis is the only Raven who can make a play on the wide-open wideout.
Fortunately for the Ravens, Vick doesn't see the open man. The first open man.
Celek, however, is also uncovered, and he runs his route directly behind Lewis. Both Celek and Maclin fly right through Lewis' zone, and he never reacts:
Age Ain't Nothin' But a Number?
This play is a microcosm of the problems the Ravens D has been facing all season. Safety Ed Reed has shown flashes of his old greatness—and flashes of not-greatness. Lewis is still a solid run-stuffer, but his pass coverage is becoming a liability.
According to ESPN, the Ravens defensive starters are, as a unit, the 14th-oldest in the NFL, about right in the middle. Though the Ravens who make the Ravens the Ravens (like Reed and Ngata) aren't getting any younger, much of the rest of the defense is less experienced.
Players like Pollard, cornerback Cary Williams and linebacker Dannell Ellerbe are in just their first or second year as major Ravens contributors, but are responsible for many of the coverage lapses.
But Lewis isn't without blame.
PFF grades him as one of the NFL's poorest-covering middle linebackers so far this season. Lewis hasn't ever finished a season with a negative PFF coverage grade; maybe time finally has caught up to him.
If the Ravens are going to return to their dominating ways, Lewis is going to have to find the fountain of youth—or the back seven has got to eliminate the communication breakdowns and missed assignments that plagued them against the Eagles and Patriots.