With a quarter of the season in the books already for most teams it’s time to take a look at an area that is proving to be one of the key facets of today’s game – pass protection.

We break down every pressure and sack surrendered over the NFL season, assigning blame to the offensive line, tight ends or backs kept in as part of the protection, to quarterbacks if they hold the ball too long or drift into pressure, or even simply leave them unassigned – unblocked plays or players left unaccounted for by design or error in the protection.

Through four weeks we have recorded how much of that pressure is down to each offensive line in the league, and what their pass blocking efficiency score is. That is a metric that measures pressure surrendered on a per-snap basis with weighting towards sacks.

This isn’t necessarily a ranking of the best offensive lines in the game (that will be breaking cover next week), or even which offensive lines are the best or worst in pass blocking, because in this metric we are not factoring in the speed and decisiveness of the pressure in the way the grading does, this is simply a measure of how much pressure each line has been responsible for through four weeks of the season.

PFF Elite pass blocking efficiency: 88.1

The Raiders have allowed eight sacks through four games and Derek Carr has been lost to an injury, but this line has the league’s best pass blocking efficiency of the season and has allowed just 19 total pressures, the lowest mark in the league, even among teams that have played one fewer game.

PFF Elite pass blocking efficiency: 85.4

PFF’s No. 1 O-line on paper heading into the season, the Eagles started slowly but have improved dramatically over the past couple of weeks. They have allowed 31 total pressures, but have been pass blocking for more snaps than all but four other teams.

3. Tampa Bay Buccaneers

PFF Elite pass blocking efficiency: 85.0

The Bucs have played one fewer game than most teams thanks to Hurricane Irma, and have consequently allowed fewer total pressures than all but the Raiders. They have also the third-best efficiency and could be even higher if they could shore up their left tackle spot.

PFF Elite pass blocking efficiency: 84.9

The Saints offensive line has allowed three sacks, nine hits and 18 hurries on Drew Brees and have done so without particularly good grades along their starting unit thanks to Brees having the third-quickest average time to throw in the league through four games.

PFF Elite pass blocking efficiency: 84.8

Tennessee’s offensive line picks up where it left off a season ago, with the exception of second-year tackle Jack Conklin, who has struggled far more this season than he ever did as a rookie. Still, the Titans line has allowed just one sack as a unit this season.

PFF Elite pass blocking efficiency: 84.1

Buffalo’s offensive line has allowed six sacks this season, but just 25 total pressures despite QB Tyrod Taylor holding the ball longer on average than any other passer in the game. The Bills' blockers have to protect for an average of 3.14 seconds per dropback, a full second longer every passing play than Oakland’s unit.

PFF Elite pass blocking efficiency: 83.6

The Steelers line has again been an impressive unit, and has been responsible for Ben Roethlisberger being sacked just four times. They have surrendered 31 total pressures and pass blocked 148 times over the season.

PFF Elite pass blocking efficiency: 81.2

A unit that has quietly been far better this season than in the past, the Jaguars offensive line has allowed just two sacks and 33 total pressures, although only six teams have been pass protecting for fewer snaps than the 134 Jacksonville have dealt with.

PFF Elite pass blocking efficiency: 81.1

The four sacks surrendered by Washington’s offensive line have come from two players, with the other three still yet to allow a sack. As a unit they have surrendered 33 total pressures from 136 pass blocking snaps, with Trent Williams the class of the group at left tackle.

PFF Elite pass blocking efficiency: 80.5

The play of RT Trent Brown in particular has been a revelation for the 49ers so far this season. As a unit this line has surrendered four sacks and 41 total pressures pass blocking for 163 snaps, but Brown is the league’s fourth-ranked tackle with an overall PFF grade of 85.7.

PFF Elite pass blocking efficiency: 80.5

The Vikings had one of the league’s worst offensive lines last season, and the additions they made through the draft and free agency have made an immediate and obvious difference. Nobody on the Vikings line has allowed more than one sack and as a unit they have surrendered 36 total pressures.

PFF Elite pass blocking efficiency: 78.9

Cleveland’s line looked extremely strong on paper heading into the season, and while they have been improved, they haven’t been exceptional. They have surrendered 52 total pressures, the seventh-most in the league, but they also have a quarterback that invites pressure and holds onto the ball longer than most.

PFF Elite pass blocking efficiency: 78.8

Atlanta’s offensive line is again strong but has had a weak link at right guard, where Wes Schweitzer has been trying to fill the gap vacated by the retirement of Chris Chester. He has accounted for seven of the line’s 39 total pressures, but has been better in recent weeks.

PFF Elite pass blocking efficiency: 78.2

While some want to decry this Giants line as horrendous, it has not been among the worst in the league, such is the state of offensive line play in 2017, and even LT Ereck Flowers is the 47th-ranked tackle in the league with an overall PFF grade of 47.0, meaning there are 17 lower-ranked starting tackles. As a unit they have surrendered 49 total pressures despite Eli Manning having the league’s second-quickest average time to throw.

PFF Elite pass blocking efficiency: 78.1

Only Matt Kalil holds this back from being a much higher-ranked line. Kalil has surrendered four of the five sacks this line has surrendered and 13-of-38 total pressures across 136 snaps.

PFF Elite pass blocking efficiency: 78.0

Baltimore’s line took a huge blow when they lost Marshal Yanda – the best guard in football – to injury for the season. Yanda only played 102 snaps, 45 pass blocks, but he had only given up a single pressure in that time. As a unit this line has surrendered 38 total pressures on 134 pass blocking snaps.

PFF Elite pass blocking efficiency: 77.7

Injuries at the tackle spots have ravaged the Green Bay offensive line. This was the best pass blocking line in football a season ago, but in 2017 it has surrendered 52 total pressures, while they had just 136 for the entirety of 2016. Only two lines have been pass protecting for more snaps than Green Bay’s 183.

PFF Elite pass blocking efficiency: 77.4

What many believe to be the best line in football has had its struggles this season. Even All-Pro's Tyron Smith and Travis Frederick have started slowly in 2017. As a unit they have surrendered 46 total pressures compared to 130 for the entire 2016 season.

PFF Elite pass blocking efficiency: 77.1

Kansas City’s offensive line has had to pass protect for 145 snaps this season but has been aided by the plethora of screens and short passes the Chiefs run on offense. They have surrendered 42 total pressures and seven sacks as a group.

PFF Elite pass blocking efficiency: 76.5

The Jets have surrendered nine sacks from the offensive line, which is more than a quarter of the total pressure they have allowed (39). They have pass blocked for just 134 snaps, the joint seventh-fewest snaps in the league.

PFF Elite pass blocking efficiency: 75.6

The offensive line is once again an issue for the Chargers, and has coughed up 50 total pressures from 156 pass blocking snaps. Philip Rivers has only been sacked twice from pressure given up by the line, but he has been under duress plenty.

PFF Elite pass blocking efficiency: 75.0

The addition of Andrew Whitworth at left tackle has been a colossal boost to this unit. Whitworth has allowed just one total pressure this season and has the league’s best pass blocking efficiency rate among tackles (having led the league a season ago). The other four members of the line have combined to surrender 39 pressures between them.

PFF Elite pass blocking efficiency: 73.7

Denver’s offensive line has allowed ten sacks, second-most in the league, while RT Menelik Watson has allowed seven of those by himself, and had given up six by the end of week two. Rookie LT Garett Bolles has given up 14 total pressures but just one sack.

PFF Elite pass blocking efficiency: 73.6

Cincinnati’s offensive line has been an obvious issue all season, with the young tackles combining to surrender 25 pressures by themselves (more than Oakland’s entire offensive line). The entire line has allowed 48 total pressures on 143 pass blocking snaps.

PFF Elite pass blocking efficiency: 73.1

With a week less playing time due to a rescheduled game, no team has been pass protecting less than the 116 snaps the Miami Dolphins have seen, but they have still found a way to surrender 40 total pressures, and sit middle of the pack for pressure allowed.

PFF Elite pass blocking efficiency: 72.4

The surprise entry this low on the list, the New England Patriots offensive line has been far more porous than it was in 2016. They have allowed 60 total pressures, the fourth-most in the NFL, with Tom Brady taking an uncharacteristically long time in the pocket on average (2.58 seconds per throw).

PFF Elite pass blocking efficiency: 72.0

Chicago’s offensive line was supposed to be a strength heading into the season, but injuries have ravaged it over the first few games and the resulting reshuffles have caused even more mahem. As a unit, they have allowed 55 total pressures on 149 pass blocking snaps.

PFF Elite pass blocking efficiency: 71.2

Another of the worst lines of 2016 has been little better this season so far. The Colts have given up 48 total pressures and eight sacks while Andrew Luck rehabs on the sideline.

PFF Elite pass blocking efficiency: 71.0

Detroit’s offensive line was in big trouble from the moment LT Taylor Decker got hurt and Greg Robinson became their starting blindside protector. Robinson has allowed 19 total pressures by himself, the same number as the entire Raiders starting unit. As a line, Detroit has surrendered 59 total pressures.

PFF Elite pass blocking efficiency: 69.7

At times there is no worse line in the league than Seattle’s, but they come in at No. 30 so far in pass blocking efficiency, having surrendered 65 total pressures, the third-most in the league. Russell Wilson has sped up his average time to throw, but still ranks the fifth-slowest in the league, putting added pressure on this unit.

PFF Elite pass blocking efficiency: 67.7

Arizona’s offensive line has been a major problem for some time now, and as a group no unit has surrendered more total pressure. The Cardinals’ line has coughed up a league-high 11 sacks and a staggering 83 total pressures through four games.

PFF Elite pass blocking efficiency: 65.5

Houston’s offensive line has been little short of a disaster without LT Duane Brown, who is in the midst of a holdout. They have allowed 68 total pressures and ten sacks as a group, and aren’t aided by Deshaun Watson having the league’s second-slowest average time to throw.