Next Gen Stats: How defensive pressure defined the 2023 NFL season

Before we fully dive into the 2024 offseason, Next Gen Stats analytics expert John Andersen takes an in-depth look at a definitive aspect of the 2023 campaign.

The San Francisco 49ers were in position to strike first in overtime of Super Bowl LVIII, facing third-and-4 from Kansas City’s 9-yard line. That’s when Chiefs defensive coordinator Steve Spagnuolo blitzed quarterback Brock Purdy for the 22nd and final time that Sunday, capping off a performance in which K.C. blitzed on a season-high 52.4 percent of dropbacks. Chiefs All-Pro defensive tackle Chris Jones went unblocked on the play, logging his team-high sixth pressure of the game and causing Purdy to throw an errant pass over the head of an open Jauan Jennings. The 49ers were forced to kick a field goal, setting the stage for what would be the game-winning touchdown drive orchestrated by Patrick Mahomes en route to the team’s third Lombardi Trophy — and his third Super Bowl MVP — in five seasons.

Jones’ unblocked pressure was the Chiefs’ ninth of the game, two more than they had previously generated in any single contest during the season, with all occurring on blitzes. It was the culmination of a season-long theme of schemed pressure at the hands of the wizardly Spagnuolo, whose young unit generated 73 unblocked pressures and an 11.3 percent unblocked pressure rate during the regular season (both top marks league-wide). Cornerback Trent McDuffie, who led the NFL with 11 unblocked pressures from a slot alignment during the regular season, generated two such pressures on Super Bowl Sunday.

While it may be true that there is no single aspect of football that determines the outcome of a game or season, a team’s ability to pass or disrupt the pass are tantamount in the modern NFL. The inability to consistently and effectively execute either of those things can be covered up by other areas of strength, but complementary football is at its most apparent when a struggling offense is covered up by dominant defense, or a lackluster pass rush is bailed out by a bullish secondary. However, any aspect of the game has the potential to tip the scales at any given time.

This was the story of the 2023 Kansas City Chiefs. The worst offense of the Andy Reid-Mahomes era — a relative distinction when compared to most offenses around the league — was constantly given second, third and even fourth chances by Kansas City’s elite defense, which accentuated how pressure does not appear uniform across the league; rather, it comes in a multitude of ways.

From a 50,000-foot view, 12 of the 14 playoff teams this season finished in the top half of the league in pressure rate, and 11 of those 14 teams ranked in the top half in pressure rate from Week 11 through Week 18, with the Bills, Eagles and Buccaneers being the exceptions. For a team like Buffalo, offensive success arrived right as pressure waned on the defensive side. For the Eagles, everything fell apart at once.

Pressure can come from a pass rusher beating the blocker across from him cleanly, from a quarterback bailing out of a clean pocket or from a quarterback holding onto the ball too long due to coverage and lack of receiver separation, among other reasons. Generating a quick pressure (occurring in under 2.5 seconds) eliminates many variables, as it’s more predicated on a pass rusher immediately beating the pass blocker off the line of scrimmage. Similar to overall pressure metrics, 11 of the 14 playoff teams this season finished in the top half of the league in quick pressure rate, with the Chiefs, Packers and Buccaneers being the deviants.

Unlike the Chiefs, the Bucs did not regularly generate pressure at a very high rate throughout the regular season or specifically down the stretch. But like Spagnuolo, Todd Bowles found a niche that worked for his unit.

Bowles sent six or more pass rushers at the NFL’s third-highest rate (12.4 percent) during the regular season, generating the second-most unblocked pressures on such pass rushes (26). This manifested in a significant strength-on-weakness matchup against the Eagles on Super Wild Card Weekend, as Philly QB Jalen Hurts ranked bottom three in yards per attempt (4.4), completion percentage (42.4%) and success rate (29.3 percent) against such blitzes during the regular season. The Bucs ended up pressuring Hurts on 57.1 percent of their blitzes in the game, with Hurts completing just eight of his 17 attempts for 69 yards on such dropbacks — which aided the Bucs in decisively dethroning the defending NFC champs in the first round of the postseason.

Whereas Bowles and the Bucs excelled in scheming up a specific kind of pressure in certain spots, Spagnuolo put on a season-long master class that will be etched in NFL history books.

The Chiefs generated pressure at the 12th-highest rate (36.7 percent) during the regular season, hitting their stride from Week 11 on, with the second-highest pressure rate (41.2 percent) in this span. Most of that generated pressure didn’t occur immediately, as Kansas City’s quick pressure rate was just 15.2 percent (21st in the NFL), while its average time to pressure was 2.78 seconds (26th in the NFL). But those high-level metrics didn’t matter come playoff time because Spags had perfected a way to confuse and outsmart opposing offenses by using disguised pressure packages that led to pressures via blitzes. Combining that with the elevated play of Mahomes and the offense, the Chiefs became the first NFL team to win back-to-back titles since the 2003-04 Patriots.

It was fitting that the season culminated with two teams that shared a similar narrative in terms of routinely creating pressure, albeit through different means.

The 49ers largely played zone coverage and relied on four-man rushes to generate pressure this season under defensive coordinator Steve Wilks. This led to a 38.5 percent pressure rate and a 17.2 percent quick pressure rate during the regular season, both 10th in the league. Wilks — who, it just so happens, was relieved of duties last week — picked his spots with the Niners, blitzing on just 21.7 percent of dropbacks during the regular season (30th) but generating pressure on 55.1 percent of those dropbacks, the second-highest rate in the league. Both of Nick Bosa‘s sacks in the NFC Championship Game came on four-man rushes, as did all three of the team’s sacks in the Super Bowl, a game in which San Francisco rushed four on every dropback up until 5:24 remained in the third quarter. Of Bosa’s game-high 10 pressures, the third-most in a playoff game since 2018, eight came on four-man rushes.

The 49ers rushed four on 89.6 percent of their pass rushes in the postseason, blitzing Green Bay’s Jordan Love, Detroit’s Jared Goff and Mahomes on just 10.4 percent of their combined dropbacks but generating pressure on 78.6 percent of those snaps. In the Divisional Round alone, Wilks blitzed Love on just 22.2 percent of his third-down dropbacks but spawned pressure on a whopping 55.6 percent of those plays. It was an area where the unit excelled during the regular season as well, with the 49ers leading the NFL with a 64.8 percent pressure rate on third-down blitzes despite blitzing on just 29 percent of third downs (19th).

The 49ers didn’t have to be exceptional from a pressure standpoint with a coverage unit featuring playmakers Fred Warner, Dre Greenlaw and Charvarious Ward, and their offense routinely scoring 30-plus points. It was largely the opposite for the Chiefs until the postseason.

Both Super Bowl participants proved a larger point: While pressure may come in different forms, it’s critical to postseason success. Neither defense led the league in any of the surface-level pressure metrics, but both found ways to generate pressure that best suited their respective personnel, ultimately helping their teams secure a spot on the game’s biggest stage.

Teams that can pass the ball more efficiently and effectively than others will win a lot of games, but those that find unique ways to disrupt the aerial attack are poised to go the distance.