Shortly after the Super Bowl loss to the Kansas City Chiefs last February, Kyle Shanahan fired defensive coordinator Steve Wilks and subsequently promoted Nick Sorensen to Defensive Coordinator, citing scheme fit and philosophy as areas of dissonance that needed change. But what differences can 49ers fans expect to see this season under Sorensen compared to Wilks?
One of the biggest differences will be in the pressure packages and coverage the team utilizes this season compared to last season. Under Wilks, the coverage of the secondary was the focus, allowing for more complicated disguises and adjustments to create advantageous matchups while asking the front to win their one-on-one matchups.
For example, in the Super Bowl against the Chiefs, Wilks presented a man-coverage look with a single safety, in what we call a "middle field closed" look. However, the Chiefs' late motion exposed the defense as a zone, and post-snap, they dropped into a 2-deep, 4-under fire-zone, middle-field open look.
The Chiefs made a good call against this, using a middle-clearing route that pulled Fred Warner deep and allowed Travis Kelce to work underneath. This netted them a first down on 3rd-and-long at a crucial point in the game.
From the end zone, you can see the scheme provides one-on-one pass-rushing challenges for the defensive line to win while trying to force Mahomes to adjust post-snap to the change in the defense—ideally giving the secondary an advantage and relying on the talent up front to win their matchups.
Later, on another crucial third down, Wilks presented a pressure look with a "middle field open" defense, using split safeties.
From there, they dropped into a 3-deep, 3-underneath fire-zone with Randy Gregory and Chase Young dropping into hook zones late.
This time, the Chiefs had Jerick McKinnon on a flare-out and were again able to beat the pressure for a first down.
From the end zone, the presentation shows the offense eight potential rushers against six potential blockers, but the defense drops three men into coverage. They do get an unblocked rusher, but the late drop of two defensive ends doesn't account well for the running back, once again leaving the defensive line with one-on-one rushing challenges.
So far in the preseason, Nick Sorensen has brought back pressure packages that were run under Robert Saleh and DeMeco Ryans, which provide a greater advantage to the defensive line in their rush opportunities but assign the coverage with more predictable responsibilities.
Here, they give a pressure presentation with a single safety look.
Post-snap, they're playing a 3-over-2 cone on the second and third receivers while manning up the outside and having Robert Beal on a peel rush, where he will pick up the running back should he flare out into the flat.
From the end zone, the presentation forces a predictable line slide, and with Beal on a peel rush, allows Malik Mustapha to be unblocked off the edge.
With the running back stepping up to pick up the inside pressure, Beal needs to recognize this and attack the offensive tackle's inside shoulder to allow Mustapha a direct line to the quarterback.
Another example, against the Saints, shows Sorensen giving a bump-man look with pressure.
Post-snap, you can see they are in physical press-man coverage while running a double stunt up front to generate a pass rush. The presentation again forces a predictable line slide and opens up a huge lane on a stunt. The idea is to disrupt the timing between the receiver and quarterback.
All four of these defensive calls allowed gains in different ways, the last being a pass-interference call. But you can see a clear philosophical change from Wilks to Sorensen, back to what the 49ers did under Robert Saleh and DeMeco Ryans.
Whereas Saleh and Ryans focused on creating favorable matchups for the line in their pass-rush scheme while keeping things more simplified on the back end, Wilks focused on keeping things complex and favorable for the coverage units while simplifying the front.
Will the 49ers' defense see a return to the form that fans were used to under Saleh and Ryans? That's the question that will need to be answered this season. Early evidence shows that fans can expect a scheme change that is much more aligned with the former than the latter.
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