As the passing offense has developed to become the dominant and most critical aspect of NFL attacks, the need for a secondary with the talent to regularly withstand aerial assaults led by a deep crop of quarterbacks has become an increasingly pressing one.

In a league where the deck is stacked heavily in favour of offenses, there is only so much even the best cornerbacks and safeties can do to keep the burgeoning ranks of exceptional athletes at quarterback in check.

Going into the 2021 season, several teams stand out as being best prepared to do that with the talent they possess in the defensive backfield.

Using advanced data, Stats Perform has ranked every secondary in the NFL by their performance in pass coverage. The rankings were produced by multiplying each player's coverage baseline by a projected target share for 2021, which is dependent on their position on the depth chart, with the results then aggregated at team level to produce that defense's coverage grade.

To look exclusively at the secondary, the results for defenders who spend their playing time almost exclusively in the box have been filtered out.

The results are very favourable for one NFC West team, though two franchises from that division are at the wrong end of the rankings, while a couple of surprise names feature among those secondaries who look ready to take a leap in 2021.

THE ELITE

1. Los Angeles Rams

Graded DBs: Jalen Ramsey, Darious Williams, David Long Jr, Taylor Rapp, Jordan Fuller

The Rams may have lost key pieces in the secondary in the form of safety John Johnson and cornerback Troy Hill but, even with the departure of defensive coordinator Brandon Staley, moving the ball on Los Angeles through the air will be an imposing challenge in 2021.

Their defensive backs' aggregate coverage grade tops the league and is 17 percentage points above average, with two-time first-team All-Pro Jalen Ramsey (20.45 per cent) and the underrated Darious Williams (21.60 per cent) each in the top 15 among cornerbacks in adjusted open percentage allowed, which looks at how often a defender allows an opponent to get open when in coverage against them, adjusted for the position they play.

Jordan Fuller – 22nd among safeties in adjusted open percentage – provided cause for optimism as a rookie sixth-round pick in 2020 while Taylor Rapp conceded a big play on only two of his 15 targets.

More progress from that duo could lessen the impact of Johnson's exit but, following highly rated defensive backs coach Aubrey Pleasant's switch to Detroit, maintaining their status as the gold standard is far from a given for Ramsey and Co. in 2021.

2. Buffalo Bills

Graded DBs: Tre'Davious White, Levi Wallace, Taron Johnson, Micah Hyde, Jordan Poyer

Buffalo's offense carried the load last season as the Bills progressed to the AFC Championship Game, though the talent in the secondary is such that they can afford to have confidence in putting more of the burden on their pass coverage in 2021.

The Bills' defensive backs rank 15 per cent above the average in aggregate coverage grading. Tre'Davious White's continuing success is a reason for that, the two-time Pro Bowler first among all cornerbacks in adjusted open percentage allowed (16.20 per cent) in 2020.

A cause for concern may come across from White after a mediocre year for Levi Wallace, whose adjusted open percentage (30.85) was close to double that of White, but the Bills have to be impressed by the progress of nickel Taron Johnson, who allowed a big play on only 14 of his 74 targets at inside corner last year.

The safety pairing of Micah Hyde and Jordan Poyer may also be hoping for a bounce-back year, the latter having allowed a burn on 13 of his 28 targets at free safety in 2020. However, in White, the Bills have a shutdown corner who can lift the play of those around him. As long as that remains the case, Buffalo's secondary should stay among the best in the league even with only marginal improvements made by his team-mates.

3. Denver Broncos

Graded DBs: Kyle Fuller, Patrick Surtain II, Ronald Darby, Justin Simmons, Kareem Jackson

The Broncos head into 2021 with questions still abounding over their quarterbacks, but there is no doubt they have a championship-caliber defense, of which the secondary looks to be the strength, their defensive backs possessing an aggregate coverage grade 14 percentage points above average.

Justin Simmons was the best defender in the NFL in terms of adjusted open percentage in 2020, leading the way by allowing pass-catchers to get open against his coverage just 14.99 per cent of the time.

The Pro Bowl free safety will have an exciting mix of experience and youth alongside him. Strong safety Kareem Jackson was ninth among all players at the position in burn yards per target allowed with 7.76. Nickel Ronald Darby (37.8) and free agent signing Kyle Fuller (40.3), inexplicably released by the Chicago Bears, each ranked in the top seven in burn percentage allowed for corners with at least 200 coverage snaps.

That pairing will be joined by arguably the premier corner from this year's draft class, Patrick Surtain II, who makes the step up to the league after a stellar college career with Alabama, which he ended by helping the Crimson Tide to a National Championship and allowing 0.93 burn yards per snap. Only three Power 5 defenders gave up fewer.

Having added Fuller and the most pro-ready corner in the draft, the Broncos' secondary could soon mount a challenge to take the crown from the Rams.

THE BOTTOM

30. Seattle Seahawks

Graded DBs: Ahkello Witherspoon, Tre Flowers, Ugo Amadi, Jamal Adams, Quandre Diggs

NFC West teams gained even more firepower at the quarterback position in a dramatic offseason, magnifying the issues for a Seattle secondary that is a long way from the Legion of Boom.

Having let Shaquill Griffin walk in free agency, the Seahawks are somewhat short on proven players in the defensive backfield, with that scarcity reflected by an aggregate coverage grade 16 percentage points below average.

The Seahawks appear to be banking on Ahkello Witherspoon making a leap he never managed with the San Francisco 49ers. Witherspoon allowed a burn on half of his 28 targets last season.

Tre Flowers' open percentage of 85.7 was the fifth-worst of all corners in the NFL, though the play of another former Niner, D.J. Reed, provided some grounds for optimism as his burn yards per target average of 8.21 put him 15th among corners with at least 200 coverage snaps.

Only three inside corners gave up fewer burn yards per snap than Ugo Amadi (1.14) in 2020 while safety Jamal Adams was not the coverage liability many cast him as, the Seahawks sack leader last season giving up a big play on 10 of his 41 targets.

Yet with Quandre Diggs coming off a year in which he conceded a disappointing 13.82 burn yards per target, this is a group with more questions than answers.

31. Arizona Cardinals

Graded DBs: Malcolm Butler, Robert Alford, Byron Murphy, Isaiah Simmons, Budda Baker

The Cardinals are under pressure to produce a playoff campaign in the third year of Kliff Kingsbury as head coach and Kyler Murray as quarterback - a look at their depth chart in the secondary indicates the offense may have to carry this team to a first postseason appearance since the 2015 campaign.

Should Malcolm Butler and Robert Alford earn starting roles, they will provide veteran presences at outside corner, yet theirs is experience that should not inspire much confidence.

Butler allowed the 10th-most burn yards per snap among corners with at least 200 coverage snaps (2.42) while Alford has not played since the 2018 season.

The strength of this group comes from two former Washington Huskies. Nickel Byron Murphy's burn yards per target average of 7.50 was the fifth-best among inside corners in 2020 and Budda Baker has established himself as one of the premier safeties in the NFL, his adjusted open percentage of 16.38 trailing only three defenders in the previous campaign.

After an offseason in which Arizona did little to address the cornerback position, the onus may again be on that pair to elevate those around them, unless Butler and Alford unexpectedly recapture their form of old.

32. Detroit Lions

Graded DBs: Quinton Dunbar, Jeff Okudah, Amani Oruwariye, Tracy Walker, Will Harris

The Lions' rebuild under Dan Campbell is likely to be slow and painful, with his first season at the helm set to be one in which Detroit give up a lot of points if the secondary cannot improve.

Detroit's defensive backs' aggregate coverage grade is 27 percentage points below average. Key to the Lions improving in that regard will be Jeff Okudah's ability to shake off a difficult rookie season and justify his status as the third overall pick in 2020.

Only two cornerbacks gave up a big play in coverage more regularly than Okudah, who did so on 43.9 per cent of his targets. Unfortunately for Detroit, one of those corners is now on their roster, Quinton Dunbar (44.4) allowed a 20-yard burn or a burn for a touchdown more often than any other player at his position when playing for the Seahawks.

Projected starter Amani Oruwariye (36.9) did not fare much better, and it would be no surprise to see rookie Ifeatu Melifonwu thrust into a prominent role early on. Melifonwu was tied-ninth for the fewest burn yards per snap (1.23) allowed among Power 5 corners in his final season with Syracuse.

Will Harris at least had an admirable 2020 at strong safety, finishing third among all safeties in burn yards per target (7.0) but free safety Tracy Walker (12.85) offered little to suggest he can help Detroit turn the ship around quickly on defense. The Lions have done a disappointing job of drafting and developing talent under previous regimes. Changing that and successfully developing Okudah and Melifonwu will be crucial to this secondary climbing out of the cellar.

ON THE RISE

Minnesota Vikings

Graded DBs: Cameron Dantzler, Patrick Peterson, Mackensie Alexander, Xavier Woods, Harrison Smith

The Vikings invested heavily in the secondary in recent times and the numbers suggest that decision could pay dividends in the coming season.

Minnesota's defensive backs rank 10th in aggregate coverage rating, performing five points better than average. They will be looking for a step forward from last year's third-round pick Cameron Dantzler, who was above average in burn yards per target (9.4) and open percentage allowed (62.3) as a rookie.

But two underrated additions could see them catapult into the top five. Patrick Peterson was considered to have endured a down year last season but his open percentage of 51.9 when playing outside corner was seventh among players to have taken snaps at that spot. Meanwhile, Bashaud Breeland, another free agency signing, was tied fifth in open percentage (52.7) among corners to have played at least 200 coverage snaps.

The presence of Breeland, who is expected to compete with Dantzler for a starting job, and Peterson gives the Vikings strong depth at corner and should mitigate the potential loss of 2020 first-round pick Jeff Gladney, whose future is in doubt amid off-field troubles.

Mackenzie Alexander's return after a year with the Cincinnati Bengals may see him start at nickel, and he will need to improve after allowing 11.16 burn yards per target from the slot last season. Safeties Harrison Smith (13.13) and Xavier Woods (16.33 at free safety) also struggled in that metric in 2020, but the pressure will be taken off that pair should their top three corners live up to expectations.

Tampa Bay Buccaneers

Graded DBs: Jamel Dean, Carlton Davis III, Sean Murphy-Bunting, Jordan Whitehead, Antoine Winfield Jr.

Tampa's secondary arguably already took a step forward as the Buccaneers claimed their second Super Bowl title last season. However, their defensive backfield is only 15th in aggregate coverage rating, Tampa coming in three per cent better than average.

Yet there were signs this group is primed to make further progress in 2021, most of which came from starting corner Jamel Dean.

Dean allowed a burn on 30 of his 64 targets, his percentage of 46.9 comfortably better than the average of 52.8 for corners with at least 200 coverage snaps, while he was 10th in the NFL at his position in adjusted open percentage (21.58).

Carlton Davis III was less impressive, giving up a burn on exactly half of his 92 targets, though the fact he conceded a big play on 25 per cent of his targets (the average was 26 among all corners) leaves room for encouragement.

Nickel corner Sean Murphy-Bunting also did a decent job at preventing big plays, conceding eight on 44 targets on the inside. Yet, despite praise for Antoine Winfield Jr's rookie year, both he and fellow starting safety Jordan Whitehead will hope to make improvements in coverage having given up 11.33 and 12.32 burn yards per target respectively.

However, with a full offseason under their belt to coalesce further, the arrow is pointing up for a young and clearly talented secondary that will again be playing behind one of the best front sevens in football after the Bucs kept the band together for another run in 2021.

Las Vegas Raiders

Graded DBs: Casey Hayward, Trayvon Mullen, Damon Arnette, Johnathan Abram, Trevon Moehrig

The Raiders secondary has received its fair share of criticism in the Jon Gruden-Mike Mayock years, with doubts cast over the merits of selecting Trayvon Mullen in the second round in 2019 and Damon Arnette in the first last year.

But Las Vegas can afford to have confidence in the secondary going into 2021. The Raiders' defensive backs ranking seventh for aggregate coverage, rating 10 per cent better than the average.

Much of the Raiders' presence in the top 10 is tied to the astute acquisition of veteran corner Casey Hayward, whose adjusted open percentage of 17.3 was the fifth-best in the NFL among players at all defensive positions, though a less impressive burn yards per target average of 11.20 reflects how often he was left on an island for the Los Angeles Chargers last year.

Las Vegas will hope Hayward can accelerate the development of Mullen, who was an encouraging 15th in burn yards per target (8.67) among outside corners with at least 200 snaps. Arnette's average of 11.69 suggests he has further to go, and he may face a competition with Hayward for the starting role across from Mullen.

Yet between Mullen's progress, the arrival of Hayward and the selection of free safety Trevon Moehrig in the second round of this year's draft, the Raiders secondary is one that looks primed to establish itself as one of the better groups in the NFL.

Moehrig allowed a big play on 20.3 per cent of his targets in 2020, giving them up at the sixth-fewest rate of all Power 5 safeties with at least 25 targets. His burn yards per target average of 6.71 was the best among Power 5 players at his position. If he can replicate that impact as a rookie, the Raiders should be in extremely good shape in the defensive backfield.