Key changes Robert Saleh will make to the New York Jets defense

Here are the biggest differences between Gregg Williams' New York Jets defense and the San Francisco 49ers defense that Robert Saleh ran. Yesterday, we took a look at some of the philosophical changes that will likely be coming on offense as the New York Jets transition from Adam Gase to Mike LaFleur. Today, we turn to the other side of the ball. Adaptability Whereas Gregg Williams has always been hell-bent upon blitzing aggressively no matter where he's coached, Saleh seems to be more adaptable. According to Pro Football Reference, the Jets had the NFL's fourth-highest blitz rate in 2020 (39.2%) and the sixth-highest blitz rate in 2019 (38.4%). In 2018, the Williams-led Browns ranked fourth in the league in blitz rate (34.0%). Blitzing at a high frequency is Williams' bread-and-butter and that is something that he has not shown he is willing to change. On the other hand, Saleh showed great malleability in this area with the 49ers. In 2019, San Francisco had a dominant defensive front that could create a lot of pressure on its own without the help of extra rushers, so Saleh let them go to work and blitzed on only 20.9% of plays, placing 29th. However, in 2020, San Francisco's four-man rush took a big hit as Nick Bosa, Dee Ford, and Solomon Thomas combined to play five games while DeForest Buckner was traded to Indianapolis prior to the season. Rather than stick with his 2019 approach, Saleh adapted based on what he had at his disposal, significantly upping his blitz frequency to help out the depleted defensive line. The 49ers ranked 10th in the league with a 33.6% blitz rate in 2020. Saleh's adaptability is an important thing to keep in mind as we go throughout this piece. We can look at San Francisco's tendencies under Saleh all we want, but the fact of that matter is that he has proven to be a coach who is far more malleable than most others. There are some basic principles he will most likely continue to carry with him - such as the 4-3 base look - but in many areas, Saleh will mold his approach to best fit the players that he has. Interchangeability at safety Saleh's safeties were not completely tethered to "free" and "strong" roles. He had both of his starters roaming all over the field. Jimmie Ward and Jaquiski Tartt were the primary starting safeties for San Francisco over the past two seasons. Ward is listed as a free safety while Tartt is listed as a strong safety, and those are certainly the two players' primary roles, but both of them take on a wealth of other responsibilities. In 2019 (when both players were healthy for most of the season), Ward played free safety on 71.2% of his snaps, but he also played 15.6% in the slot and 12.8% in the box, throwing in a tiny 0.5% slice of the pie at outside cornerback. Tartt, meanwhile, played 48.8% of his snaps in the box, 13.4% at slot corner, and 1.5% at outside corner, but still played free safety 36.2% of the time. Saleh likes to run a lot of looks in which both safeties drop back deep (resulting in both players being labeled as lining up at "free safety" on the same play). In 2020, the 49ers ran a Quarters coverage (Cover-4) on 18.1% of their defensive plays, the fifth-highest rate in the league. They ranked 15th in Cover-2 usage as they ran it 15.3% of the time. Should they both return as starters, look for Ashtyn Davis and Marcus Maye to both handle all aspects of the position in some capacity while consistently covering alongside each other in Cover-4 and Cover-2 looks. Linebacker usage In Gregg Williams' 3-4 defense, the Jets typically had two off-ball linebackers who would play on every down. Neville Hewitt and Avery Williamson were the opening-week starters here. On the edge, two outside linebackers would generally play from 50-70% of the defensive snaps, with a defensive end kicking out to handle the edge whenever one or both went to the sidelines. Tarell Basham and Jordan Jenkins were the starters here. A 4-3 base defense employs the linebackers a little bit differently. There will still be two every-down off-ball linebackers - for the 49ers, these were Fred Warner and Dre Greenlaw for most of the past two seasons - but only one other linebacker will get any playing time in most games. This player generally subs in for anywhere from 20-60% of the snaps depending on how often the base 4-3 look is deployed. Azeez Al-Shaair played this role for the 49ers over the last two seasons, while Kwon Alexander dabbled in it during the 2019 playoffs. The required traits for linebackers in these defenses are also different. In a 3-4 defense, muscle and grit to defend the run are a bit more important due to the depleted amount of size up front. However, in a 4-3 defense where there is one more big man on the line of scrimmage and one fewer athlete off the ball, toughness and run-stopping become a bit less important while range and coverage ability take a front seat. Hewitt and Williamson are tailor-made 3-4 inside linebackers with their strength, hit power, and toughness against the run, but both are slow-footed athletes and brutal in coverage (Williamson used his instincts to provide decent coverage throughout most of his career, but he was a major coverage liability post-ACL injury). In San Francisco, Warner and Greenlaw offered the excellent coverage skills that are necessary to play every down as an off-ball linebacker in a 4-3. C.J. Mosley played in a 3-4 defense throughout his Ravens career, but he should fit just fine in a 4-3 defense. Mosley is more athletic than given credit for (we'll see how he looks after nearly two whole seasons off) and has outstanding fundamentals and instincts in coverage. The Jets need to find a starter to place beside Mosley who has the athleticism, range, and coverage ability to hold up as an every-down player in a 4-3 defense. Las Vegas' Nicholas Morrow (broken down here) and Tennessee's Jayon Brown (broken down here) are two free agents in their primes who fit the bill. Seattle's K.J. Wright may soon be turning 32 years old, but he remains one of the NFL's best cover linebackers, has plenty of experience in a 4-3 defense, and shared time with both Robert Saleh and Jeff Ulbrich in Seattle. In addition to the two starters, the Jets need a reliable third linebacker who will typically be expected to play about one-third of the game. Al-Shaair played 29% of San Francisco's defensive snaps in 2020, appearing on somewhere from 20-58% of the snaps in 10 of his 16 games. With the Falcons under Jeff Ulbrich, Mykal Walker was Atlanta's third 'backer, playing 36% of the snaps and appearing for somewhere from 15-56% of the snaps in 15 of his 16 games. These two players provide a guideline for how often we might see the Jets deploy their third linebacker in 2021. Blake Cashman is a good candidate to fill this role if he can remain healthy. He may not have a complete-enough toolbox to handle a starting role, but if used on a situational basis, his athleticism and coverage tools could shine while his issues against the run are masked. The Jets could also search for someone to fill this role in the middle rounds of the draft. LSU's Jabril Cox comes to mind as a picture-perfect target. Whatever happens, Neville Hewitt (an unrestricted free agent) cannot be starting for the Jets in 2021. He offers some nice skills that make him worthy of having on any NFL roster, but he would be eaten alive in coverage if asked to start for a 4-3 defense. The Jets have some work to do before this linebacker core is ready for the scheme change.