It's a classic football precept: Great teams build from the inside out. It's not quite true, however. Let's be honest, the best thing you can have is a good quarterback. But good blocking is an important part of a strong NFL offense. The "skill players" get the headlines and the fantasy football numbers, but offensive linemen break open those big holes for your running backs and keep your quarterback upright.

Unfortunately, judging offensive lines with stats can be confusing. Rushing stats are distorted by long runs, for which the blocking didn't matter after the first few yards. Passing stats are distorted by the fact that some quarterbacks are simply more prone to be sacked than others. Nonetheless, we do have some stats that attempt to analyze the offensive line, and by looking at both passing and rushing stats we can get a good idea of which lines have done the most to help teams be successful through the first five weeks of 2015.

To determine the top offensive lines so far this year, I averaged each team's rank in five categories:

Adjusted line yards (ALY): a Football Outsiders metric that splits value between the blocking and the back, based on the length of the run and adjusted for situation and opponent.

Stuffed rate: how often running backs are stuffed for a loss or no gain, the most blocking-dependent part of ALY.

Adjusted sack rate (ASR): sacks (and intentional groundings) per pass play, adjusted for situation and opponent.

Pressure rate: how often the quarterback is under duress, including both sacks and hurries, according to ESPN Stats & Information charting.

Penalties per game by offensive linemen; this category had half the weight of the other four.

Further explanation of the first three categories, with updated numbers, can be found here. Ranks listed below do not include Monday's Chargers-Steelers game.

Here are the top offensive lines through Week 5:

If Sunday is the first time you watched the Bengals all year, this No. 1 ranking might surprise you. Maybe the Cincinnati play that stands out in your memory is the blown blocking assignment that got Rex Burkhead crushed on a jet sweep and led to a fumble recovery and touchdown for Seattle. But that play was shocking precisely because the Bengals' offensive line has worked together so well for the last two seasons. It is one of the league's best-performing but least-publicized units.

Cincinnati has a well-rounded front that excels both on running and passing plays. The Bengals rank among the top eight teams in four of the five stats that we're using to measure offensive lines. In 2014, they ranked among the top 11 teams in those same four metrics. The exception is penalties, where the Bengals were average last season and rank 25th so far in 2015.

The best player on the line is left tackle Andrew Whitworth, who allowed only a half-sack in pass blocking last year but couldn't even get a spot in the Pro Bowl. In the nine seasons before this one, Whitworth only has one Pro Bowl appearance (2012), and none of the other Bengals linemen have made a Pro Bowl. That really needs to change this season.