The sky over Arrowhead Stadium was ashtray gray. A constant downpour in Kansas City had soaked the grass field and bloated it like a sponge. Three times before the opening kickoff, a blistering wind blew the ball off the tee. The conditions seemed perfect for a physical ground battle between division rivals like the Raiders and the Chiefs, the kind of brutal turf war the game's leathery old-timers claim to love.

Then QB Rich Gannon and the top-ranked Raiders offense took the field and, seemingly oblivious to the 83 years of pro football tradition they were about to trample, began chucking the ball all over it. On the first play of the game, wideout Tim Brown turned around at the line of scrimmage and put up his hands. Dink. That was followed by a two-yard flare to Brown. Donk. Next came their standard crossing route, Two Jet Flanker Drive: completed to Brown again for eight yards. Dank. Then TE Roland Williams ran a crossing pattern right across the line of scrimmage for another six yards. Dunk.

Eight passes in the first 10 plays. Empty backfields. No fullback. Four wide receivers, sometimes five. Tight ends split out to the numbers.

The more it rained, the more the Raiders threw. First down? Pass. Short yardage? Pass. Clock management? Pass. In all, the Raiders took 72 snaps and let it fly 55 times, completing 35. It was an all-out air raid. It was, to borrow a vibe from halftime of Super Bowl XXXVI, NFL-evation.

It's not just Oakland. What seemed an anomaly in Week 1, when Pats quarterback Tom Brady passed 25 times in a row to beat the Steelers, has become commonplace. In Week 10, two unheralded quarterbacks, Pittsburgh's Tommy Maddox and the Rams' Marc Bulger, became the first pair of passers to throw for at least 450 yards on the same Sunday. The next night, Gannon completed 21 passes in a row and finished 34 for 38 in a 34-for-10 rout of the Broncos.

This season, in a league where change normally occurs at a glacial pace, a seismic shift is underway. For more than two decades the run-to-pass ratio has not dipped below 50/50. In 2002, passes have blown past runs to the tune of 58/42. Three yards and a cloud of dust? Try 13 yards and a vapor trail.

It's common for one or two teams each season to "overemphasize" the pass, says Chiefs coach Dick Vermeil, but now everyone's doing it. The NFL's top 10 offensive teams, all playoff contenders, are passing more than they run, with Oakland (66%), Buffalo (63%) and New England (62%) leading the way. In the past decade, only Drew Bledsoe has completed more than 400 passes in a single season; right now five QBs could reach that mark.

Vermeil knows about the passion for passing. As the Rams coach in the late '90s, his prolific offenses pushed the bar -- and the ball -- further than ever before. Mike Martz locked up his job as Vermeil's offensive coordinator after one interview question. "What's your thinking about the short pass?" Vermeil asked. Martz answered, "I'm gonna use it like a long handoff."

Bingo.

In the 1970s, Don Coryell tested the limits of the game by passing downfield no matter what down it was. In the 1980s, Bill Walsh stretched offenses horizontally by utilizing the space between the numbers on the field and the sideline. In the 1990s, the run 'n shoot and the k-gun revolutionized movement behind the line of scrimmage with the no-huddle, the shotgun and multiple-receiver formations. What you're seeing now is the only logical way the offensive game can expand.

What started with two wideouts and expanded to four is now maxed out with an empty backfield, five receivers and mind-dazzling pre-snap shifting. When Vermeil started with the Eagles 26 years ago, his offense had five pass-protection packages. Now Vermeil's Chiefs have 25.

What's not surprising is that while pass completions are going up, yards per catch are going down. The quarterback's first read used to be the wideout 25 yards downfield. Now it's the slot receiver on a five-yard out. The pass is no longer an occasional weapon to wipe out long-yardage deficits. It's an option no matter what down or how many yards to go -- and increasingly, the option preferred over the classic tackle trap.

	Drew Bledoe has been airing it out.

There's little question which plays work better. The Bills average 4.3 yards per rush; they get 7.5 yards per pass attempt. Think about that for a minute. If you run 70 plays, that's a difference of 2 1/2 football fields -- in a game of inches.

As a result, teams like the Saints have all but deleted antiquated running plays from their playbook, replacing them with passes. Out: power sweeps. In: flare passes. Saints offensive coordinator Mike McCarthy explains that his O needs all 11 men performing perfectly to gain four yards rushing. But as long as the quarterback and the receiver are in sync, they can get twice as many yards on a little flare, even if breakdowns occur all over the place.

Pass or run? It's a no-brainer.

Just like in the NBA, where positions and roles have begun to bleed together, the evolution of the passing game has created the need for interchangeable multiskill players. Running backs who catch like wideouts. Receivers quick enough to run like backs and big enough to block downfield like tight ends. Tight ends who can do all of the above.

"This is not a revolution that may happen some day, this is going on all over the league," says Chiefs vice president Lynn Stiles, a 23-year NFL veteran who began his career on Bill Walsh's staff in San Francisco. "The passing game has expanded to a point where, I'll tell you what, the NFL has outgrown its field and we need to look into expanding the dimensions of the field."

Don't laugh, it could happen.

With NFL-evation, it's all up in the air.

MORE BIG BANG: NFL 2010 I Control Freak I Confidence Game I Perfect Fit I Triple-X I Flight Plans

This article appears in the December 9 issue of ESPN The Magazine.