All the record-breaking, high-flying fireworks produced by NFL offenses during the season's first two weeks has everyone cooking up theories around the backyard barbeque. But there's a pretty good argument to be made that in a year with a truncated offseason, the primary force behind all this prolific offense has to be the groups of players who make up at least 45% of every offensive unit: The linemen. Every piece of choreography in the NFL's ballet of brutality starts with these five heavily padded oafs. "Your big guys are really the foundation of what you do on offense," says Tony Boselli, a former offensive lineman. "Teams that have a better, or at least a solid offensive line have a better chance." The play of offensive lines is hard to measure. While teams go to great lengths to grade linemen, there are no official statistics presented to the public. Some of this is a result of football's secretive nature. It's difficult to evaluate the play of a lineman without knowing what his blocking assignment was on a given playand that's something no team is going to offer up. Without knowing what a player was supposed to do, it's impossible to know for sure whether he should get credit for making the correct block. Not all members of an O-line have the same level of responsibility, either. Left tackles, for instance, have to block the toughest pass rushers, while centers often have help from the guards to their right and left. The only way to judge this is to employ someone with an educated eye to spend hour after mind-numbing hour watching every lineman's performance on every play. For the past three full NFL seasons, a small outfit called Pro Football Focus has been doing just that. Based, quite incongruously, in the U.K, this company has a staff of 18 analysts who break down every game. Four are responsible for grading offensive linemen and together they've tabulated about 500,000 blocks over three full seasons. Each analyst spends somewhere around six hours per game studying film, according to Pro Football Focus's founder, Neil Hornsby. Each time a lineman attempts a block on a running play, he's given a grade on whether or not he was successful. On passing plays, the linemen are graded down when they allow a sack, a hit on the quarterback or defensive pressure that affects the play. The grades are based on how a player's score compares to the overall average for the position. "There is absolutely no guessing," says Hornsby. "We don't grade down anybody unless we're 90% sure what was supposed to happen." The company makes some data available to the public, but the company's more-advanced stats are held back and are purchased by NFL teams and analysts. Hornsby says five or six players have subscribed to Pro Football Focus and haven't been shy about voicing displeasure if they believe they've been erroneously graded. After last year's Super Bowl, he says, Green Bay Packers lineman Josh Sitton disputed a sack that was credited against him (Hornsby agreed and changed his score). Earlier this month, he says, another lineman emailed him to say he wasn't responsible for a hit to his quarterback that was tied to him. Again, after further review, Hornsby removed it.