But there have already been 44 individual 300-yard passing games this season. That is not just the most through the first four weeks of a season, it is also the most through the first seven weeks of any season.

Last year there were 96 individual 300-yard games in the entire season; in 2006 there were 65. In the meantime, there have been 26 individual 100-yard rushing games, a figure that reflects in part the trend of teams dividing carries between two backs. There have also been eight individual 400-yard passing games, just five short of the record for a full season.

The outpouring of passing delights offensive coordinators as well as television executives, who know that high-scoring games produce good ratings. But it also raises the question of what combination of forces converged to produce such a sharp spike.

There are several answers, say those who watch and shape the game. The most obvious is that when something works for one team — Green Bay last season was forced to go pass-heavy because of injuries — everyone tries to copy it.

More teams are spreading the field to create better offensive matchups, particularly in the middle of the field, where most of the action and mismatches take place in the short and intermediate passing game. It is no accident that New England’s Wes Welker, who toils in the middle of the field, is the league’s leading receiver.

Most coaches think their third receiver is better than the opponent’s third cornerback, that the tight end — think New England’s Aaron Hernandez and Rob Gronkowski — is a brutal matchup for a linebacker, that a running back sent out for a pass is better than the linebacker forced to cover him.

“Once you extend a linebacker and get him out of the box, that’s not his world,” said Herm Edwards, the former Jets and Chiefs coach who is now an ESPN analyst. “You make somebody miss in space. Corners and safeties are used to running at angles, but linebackers’ angles are different. Before, these formations were more prevalent in two-minute situations, when teams were behind, but maybe you saw it 15 times a game. Now you might see it 30 times.”