Leading up to the 2014 season, the 49ers pass defense was widely considered to be the weakest aspect of an otherwise talented and deep roster. San Francisco was replacing three-quarters of their starting secondary, expecting a rookie to play a significant role as the slot corner, and were going to be without their All-Pro pass rusher for at least half the season. Fast forward 11 weeks and the 49ers somehow field the best pass defense in football.
When they’ve slipped up, they’ve slipped up big — the dismantling at the hands of Peyton Manning and the Broncos and second half collapses against the Bears and Cardinals. Otherwise, San Francisco’s pass defense has far exceeded even the most optimistic of expectations, and even stranger, they’ve done it against what Football Outsiders considers to be the fifth-most difficult slate of opposing offenses. The scariest part? There’s plenty of reason to believe this unit is only going to be better over the final six weeks of the year.
Part of the reason San Francisco’s success defending the pass has been so surprising is that they’ve been able to do it without the presence of a consistent pass rush. Justin Smith has had his moments where he bullies some poor guard five yards backwards into the quarterback’s lap and Aaron Lynch has progressed steadily since claiming a significant role in the second month of the season. But while those two players have been the Niners’ best pass rushers through 10 weeks, they combined for just five sacks entering last week’s contest in New York.
Against the Giants, things changed dramatically. Thanks to a couple of desperate heaves that somehow avoided intentional grounding penalties, the 49ers took Eli Manning to the turf only twice. But that doesn’t begin to capture how frequently San Francisco’s front bothered Manning in the pocket.
According to Pro Football Focus, Manning was pressured on 51.1 percent of drop-backs. It was the first time all season San Francisco pressured an opposing quarterback on over half of his drop-backs and that pressure rate was well above the 29.3 percent mark the 49ers had entering the game. Perhaps even more importantly, San Francisco was able to create that pressure with four or fewer pass rushers on all but two snaps.
Of course, there was one minor difference between that Giants game and the previous nine: the 49ers got that All-Pro pass rusher back. Aldon Smith returned from suspension to play 77 percent of San Francisco’s defensive snaps, primarily in the Niners’ sub-packages over the final three quarters. It would have been fair to expect some level of rust after missing the first half of the season, but if Sunday was rusty Aldon Smith, the five quarterbacks left on San Francisco’s schedule should be very worried.
Smith’s first pressure of the game came with 4:48 remaining in the second quarter and the Giants threatening to score.
The 49ers are in their nickel package with their front four spread wide. Like he’s done so many times in the past, Aldon takes a step to the outside before looping around through the A-gap on a T-E stunt. Neither Weston Richburg (70) or J.D. Walton (55) are able to recover in time and Aldon gets a free run at Eli, forcing an errant throw over the middle to Rueben Randle.
San Francisco’s defense has been fantastic on early downs this season, but if there’s one area where they’ve had some issues, it’s been on third down. Early in the third quarter, with the Giants facing a 3rd-and–13, we get an example of how Aldon’s presence on the field should improve that aspect of the 49ers pass defense.
Vic Fangio calls for a T-E stunt on each side of the defensive line. Unlike the last play, the Giants slide their protection in Aldon’s direction, opening up the opposite A-gap for Lynch. Because of the down and distance, Manning has to hold on to the ball waiting for routes to develop downfield which gives Lynch enough time to close the gap and bring Eli down for the sack.
Lynch had previously been the player that opposing offenses had to worry about most when protecting the passer. That’s no longer the case. With more advantageous opportunities like the play above, expect the production from the rookie outside linebacker to surge over the final six games of the season.
In the fourth quarter, Aldon started to look even more comfortable and came up with several notable plays. New York’s first possession of the quarter came to an end when with a Chris Culliver interception that was setup by pressure from the 49ers’ edge rushers.
Tackles Will Beatty (65) and Charles Brown (71) each get beat with ease, getting their hands knocked down and allowing Aldon and Lynch to get the edge. San Francisco’s pass rushing duo converges on Eli, forcing another errant throw that results in Manning’s fourth interception of the day.
Aldon closed the game strong, pressuring Manning on three of the Giants’ final four plays of the game. The first of those featured an interesting wrinkle that I can’t remember seeing from Aldon previously.
The 49ers start this play like numerous others in the game by looking to run their T-E stunt to each side of the line. However, after his initial step to the inside, Aldon loops back around the edge. Because Beatty and Richburg have already begun to exchange the expected stunt, Beatty is occupied with Justin Smith and has no chance of reacting quickly enough to reach Aldon on the outside.
The play doesn’t end in quite the fashion that you would’ve hoped as Eli again manages to get the ball out, dumping the ball off to Andre Williams in the flat and preventing a sure sack. But it was interesting to see this new — or at least little used — wrinkle in the 49ers’ stunt game. As if the return of Aldon alone wasn’t enough, this will give opposing offensive lines something else to prepare for.
Aldon finished the game with eight total pressures (two hits, six hurries) with Lynch adding another eight from the opposite side. Those 16 pressures are more than the 49ers have managed in seven different games this season.
While there were definitely times when the Giants were devoting extra protection to Aldon’s side of the field, it didn’t happen as often as you might’ve expected. New York would occasionally slide protection his way or flex a tight end out to his side to chip before going out into the route and those things really didn’t start happening until the latter portion of the third quarter. But you also saw those same type of protection adjustments to the opposite side of the line, with the Giants trying (and mostly failing) to help Brown, their backup right tackle, keep Lynch under control.
What you did see a good amount of was the Giants keeping six or more in to protect, even though the 49ers were only sending four (and sometimes three) after the quarterback. This means fewer Giants receivers were going out into the route against seven or eight 49ers defenders in pass coverage. The results speak for themselves: Eli finished with a completion percentage below 50, five interceptions, and performance that was over 200 yards below replacement level.
With a terrible Washington offensive line — that will likely be without standout left tackle Trent Williams — on the horizon, Aldon Smith looks to be in for another big day. It’s difficult to overstate the impact a dominant pass rusher can make for a defense. If San Francisco ultimately finds themselves back in the playoffs for a fourth straight season, you can expect that Aldon "balling out" is a big reason why.