NFL's best and worst O-lines

The San Francisco 49ers' offensive line is an elite group of players. Michael Zagaris/San Francisco 49ers/Getty Images

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

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.