Unless you watch every snap of every game, it's nigh on impossible to evaluate offensive line play. You can infer some things from numbers, but that can often lead to incorrect conclusions.
For example, logic would say that Aaron Rodgers getting sacked the most of any quarterback means he has the worst pass-protecting line, right? Except that conclusion overlooks the fact eight of those sacks were due to Rodgers' decisions and another two were the results of skill position players not picking up the pass rush. It also doesn't consider the fact Rodgers is guilty of having the sixth-highest average time to sack (from when the ball is snapped) of any player in the league.
With our game charting and grading, however, Pro Football Focus accounts for those factors. And that is why the Packers are the 11th-ranked pass-blocking line in our rankings.
This season, we've seen how poor line play can totally cripple a team -- not to mention a quarterback. But which are the best and worst lines in the league? Let's take a look.
The maulers -- San Francisco 49ers
2012 offensive line rankings
Pro Football Focus grades every play of every game to evaluate the performance of the offensive line. On any given play, a player will get a positive or negative score between plus-2.0 and minus-2.0 (with 0 being average) depending on how well or badly they executed their assignment. All plays get tallied up and normalized to account for total snaps played to generate the game grade. The grades below represent the cumulative total of all offensive lineman game grades for each team. Overall grade combines elements of pass blocking, run blocking and penalties taken. For more on PFF's grading methodology, click here.
In our pass protection rankings, the 49ers could only finish 12th. Yet their run blocking is so much better than any other team that they're comfortably our top graded line out there.
You could really pick out any member of the unit and call them a star, with every one building a case toward a Pro Bowl or even All Pro nod. For me the star of the unit is Joe Staley. Yes he's given up six sacks, but look past that. He's given up just 19 total quarterback disruptions on 384 rushes and has a run-block grade that puts all other tackles to shame.
The big change in this group from 2011 to 2012 is the addition of Alex Boone. Not only should he be under consideration for a Pro Bowl spot, but when you consider he's replacing a guy who is currently our third-lowest ranked guard on the year (Adam Snyder), you see a dramatic swing in production from the right guard spot. This is as good a line as I've seen during my time with PFF.
The maligned -- Arizona Cardinals
How do you sum up this line? Some of the problems you can't put on them. As bad as Levi Brown had been for Arizona, his improvement in the second half of 2011 made his loss in 2012 a bitter blow. But how they could start D'Anthony Batiste at left tackle for nine games is beyond comprehension. There can't have been many tackles in NFL history as badly overmatched as he was, with his 88.6 pass blocking efficiency rating ranking as one of the all-time worst since the metric was created.
When you compound that by handing out sizeable deals to a perennially poor performer like Snyder, you're asking for trouble. You have to question the front office and scouting department in that regard.
For all the negativity (and they are our lowest ranked line) there are some positives. Bobby Massie was apparently sick of being at the bottom of our rankings and has done something about it; Daryn Colledge is grading positively for the year; and even seventh-round tackle Nate Potter has shown more in three starts than Batiste did all season. While it's getting better, the Cardinals' line still has a long way to go to even be considered adequate.
The injured -- Philadelphia Eagles
It may seem odd but Philadelphia finds itself a very creditable 17th overall in our rankings. That's way down on its second-place spot in 2011, but given the amount of injuries the Eagles have had it's not bad at all.
Losing Pro Bowl-caliber players like Todd Herremans and Jason Peters will always hurt your team, but the Eagles can be happy that their investment in Evan Mathis paid off. He was our top-ranked guard last year, and hasn't rested on his laurels this year.
Their position in the rankings will likely be a surprise, but it's important for everyone to remember that blocking for a guy like Michael Vick is different than blocking for almost any other quarterback. Indeed, the average time of sack for Vick was 4.02 seconds, the highest in the league. It is very tough for any offensive line to sustain blocks for that long.
If Peters, Herremans and Jason Kelce can return next year, don't be surprised to see this line dominate, whoever the quarterback and head coach are.
The underrated -- New York Jets
This is really going to surprise some people. I maintain that Jets fans have been spoiled in recent memory by having the league's best offensive line. Now any drop feels like a plunge into mediocrity, but that's just not been the case.
Nick Mangold isn't having his most consistent year, but is still playing some fine football. Both guards are playing above average, even if Matt Slauson is struggling in the run game. And D'Brickashaw Ferguson? Well, he hasn't given up a sack and has been near shutdown on the blind side.
No, this unit is being made a scapegoat. They've gotten better and better since moving on from Wayne Hunter, with Austin Howard making up for some pass-protection problems with some good work in the run game. The real problem is that when they do allow pressure, their quarterback (Mark Sanchez) is so bad at dealing with it that it makes the pressure stand out that much more. As it is they've allowed only 97 combined sacks, hits and hurries -- seventh fewest in the league.