Since the Philadelphia Eagles named Chip Kelly head coach way back in January, much of the attention has been on his unique offense and which quarterback is best suited to run it. Kelly’s arrival also meant a shift in philosophy for the defense, though, as he installed Bill Davis at defensive coordinator and they immediately began moving away from a traditional 4-3 alignment in favor of a 3-4 base.
There were serious doubts as to whether Davis had the personnel to make such a drastic change over the course of one offseason. Interior linemen became defensive ends, defensive ends converted to outside linebackers and nose tackle was practically unaccounted for. Yet despite numerous question marks along the front seven heading into this season, the 3-4 is already paying dividends.
The Eagles may be ranked dead last defensively based on the NFL standard of total yards, but actually, Davis’ unit has held opposing offenses to 21 points or fewer in seven of nine games this season. It’s a remarkable turnaround from 2012, when the defense surrendered at least 21 points in each of their final 11 games.
The biggest difference from this season to last has come in the passing game, where, again, the Birds are deceptively good. Philadelphia is 32nd out of 32 teams through the air as well, only opponents’ passer ratings tell a different story. Quarterbacks are posting an 84.6 efficiency score against Davis’ D, which ranks 15th overall and is down 15 full points compared to a year ago when they finished 31st.
The scheme is working, and the explanation is fairly simple. The Eagles are generating pressure on quarterbacks, and they’re able to do so while lacking premier pass-rushers.
One of the primary reasons many coaches prefer the 3-4 is due to its unpredictability. A simple four-man pass rush out of a 4-3 is generally the ends and tackles that comprise the defensive line. They may use various moves or throw in a twist on occasion—a linebacker or defensive back may blitz—but the offense has a general idea of who is coming and where they are coming from on any given play.
In a 3-4, that fourth rusher could be coming from anywhere. It could be either outside linebacker, or it could be one of the interior linebackers. Blitzes can be more exotic still, because now there are multiple rushers who have the element of surprise. It’s far easier to disguise where the pressure is coming from, far more difficult for the offense to diagnose before the ball is snapped.
The difference is night and day, especially in Philadelphia where the unimaginative Wide 9 was implemented the previous two seasons. In 2011, it gave quarterbacks fits as the Eagles tied for the NFL lead in sacks with 50. By the following year, the league had figured it out, and the Birds finished 25th with 30—nearly half as many.
Notice how offensive lines adjusted their protections. What makes the Wide 9 different from a typical front is all four defensive linemen are selling out for a sack on every play. That knowledge actually made it easier after awhile though, as tackles became content to let the defensive ends run themselves out of the play. They’re getting way too deep in the backfield without any significant push up the middle.
According to Football Outsiders Almanac 2013, the Eagles sent only a four-man rush on 77.8 percent of all snaps, which was the highest percentage in the league. It’s no wonder things got stale.
Now let’s take a look at Philly’s pressure packages in the 3-4, starting with the pre-snap phase. Who’s coming?
This is a six-man pressure, and the one person, other than the down linemen, whom the offense expects to rush—converted defensive end Trent Cole—drops into coverage instead.
Even if the quarterback would’ve had time to get this throw off, Cole drops right into his passing lane. It’s essentially a two-man route, and the other receiver is blanketed.
Here we go again. Who’s coming?
Most of the defenders bail at the line of scrimmage, so the Eagles are only bringing five this time. The look still causes confusion, though, and outside linebacker Connor Barwin is going to wind up with a free run at the quarterback.
It's not like there’s time to survey options in that situation, but what’s also helped are improvements in the secondary, specifically at cornerback.
Davis is comfortable using free-agent additions Cary Williams and Bradley Fletcher in one-on-one coverage on the outside, as opposed to the sieves that were Nnamdi Asomugha and Dominique Rodgers-Cromartie last year. That said, the pass rush makes Williams and Fletcher look good, too.
Like many statistics relating to the Eagles defense, don’t be deceived by their low sack total. Philadelphia is ranked just 23rd currently with 19 quarterback takedowns.
Game-charting numbers by Pro Football Focus (subscription required) tell the whole tale. Last season, the Eagles were credited with 160 hurries and 49 hits. In 2013, PFF already has the Birds down for 141 hurries and 35 hits, so they’re likely to surpass both of the previous year’s totals. They’ve already batted more passes at the line of scrimmage—nine to six.
What it all means is while the Eagles don’t have any players putting up gaudy numbers, Bill Davis has been able to maximize their output in a 3-4 scheme. Sacks or not, quarterbacks are moving their feet and fleeing the pocket, making for some uncomfortable days in the backfield. Just imagine how much further along this unit could be in year two of the Chip Kelly experiment.