The Rules have changed and so, too, have the statistics on spirals floating high and deep in stadiums across America. This is the season of The Passing Fancy in the NFL, with a whole caboodle of kid quarterbacks cranking it up, and up, and up.

In 1977, NFL owners were bored with their game. Too predictable. Too much running. Too much defense. Too Tall and Too Dull. So they liberalized the pass-blocking rules and restricted contact with eligible receivers to a five-yard zone beyond the line of scrimmage.

As a result, quarterbacks got a few more precious seconds to spot men downfield. And the whoosh merchants on the flanks could get from here to there in a hurry. Shazam, the changes clearly have juiced up the game. Too terrific. Consider that in 13 weeks, a quarterback has thrown for 300 or more yards on 33 occasions. In 1977, there were only three. Of the 33 300-plus performances, 16 were winning efforts.

Scoring is up 16.3 percent, compared to the first 13 weeks of 1977, almost one touchdown per game. There have been 78 more touchdown passes this season than in 1977, with a startling 28 percent increase in average passing yardage per game.

Joe Namath's season passing record of 4,007 yards is being threatened by Dan Fouts in San Diego and Brian Sipe in Cleveland. Fouts needs one more 300-yard passing game to tie Namath's old record of six; Sipe needs two. m

And all that pitching also has meant prosperity for the catchers. In 1977, there were 45 100-yard receiving days by receivers. So far this year, there have been 100. In Drew Pearson and Tony Hill, the Dallas Cowboys probably will have the first pair of 1,000-yard receivers in NFL history.

"People always used to say that three things happened when you passed and two of them were bad," Fouts said the other day. "But I think there's a whole new school of thought on that, at least here in San Diego.

"The most important statistic we're concerned with is yards per play. If you can get six yards for every pass attempt, that's sure a lot easier than running it. Sure it takes courage to throw, but our coaching staff has it. We're confident throwing the ball. We're 10-3 doing it, and that ain't half bad."

All around the league similar philosophies abound. San Diego and Pittsburgh. No. 1 and No. 3 in the AFC passing stats, lead their respective divisions. New Orleans, tied for first n the NFC West, is third in conference passing, and the Cowboys, still n contention for a playoff spot, lead the NFC in throwing.

And the trend seems likely to continue, with a flock of precocious passers performing all around the league.

Eighteen of the league's top 28 rated quarterbacks are 30 or younger, and that doesn't include the likes of injured Gary Danielson of Detroit, Bert Jones of Baltimore, and Vince Evans of Chicago. Four rookies will start at quarterback for NFL teams today.

Does anyone miss Sir Francis Tarkenton, Furnace Face Kilmer or Broadway Joe Namath, with the likes of Sipe and Fouts, Joe Ferguson in Buffalo, Joe Theismann in Washington, Jim Zorn in Seattle, and many more flinging footballs around the league?

Once, NFL nabobs insisted a man wasn't ready to play quarterback until he served a five-year apprenticeship. Youngsters such as Phil Simms in New York, Steve Fuller in Kansas City, Doug Williams in Tampa Bay and Tommy Kramer in Minnesota are disproving that notion every week.

"I've never adhered to that five-year rule," said New York Giant General Manager Goerge Young, whose team starts rookie Simms. "It sure didn't take Unitas that long, or Bert Jones, or a lot of guys. I do think it takes two or three years before he can function without the offense being burdened by him.

"Our guy, I think, is also an exception to the rule. He's a student of what he's doing. He's also a leader, a guy who competes. He's got fire, and we've been pleased with him since the day we got him. Before we played him though, we wanted to make sure the team was ready for him and he was ready for the team. So he sat, and he watched, and he learned. And now he's playing very well."

Adds Bobby Beathard, general manager of the Redskins: "Some teams have just been forced to get the kids in there and get them ready. Detroit with Jeff Komlo is an example. They had no choice. But next year, when Danielson come back, they'll have two experience guys back there, and that will help them.

"If you're in a position like Pittsburgh or Miami, you can bring a young quarterback along slowly. But there are 28 teams and there are not 28 top quarterbacks ready to step in. So it takes a Joe Ferguson a little while, it takes a Sipe, a Fouts some time. And now you're seeing the results of that learning process."

Fans also are seeing more and more quarterbacks following coaches' instructions from the sideline or press box, rather than calling the plays themselves. Sixteen of the 28 teams now are taking the burden of play-calling from the quarterback.

"The trend obviously is in that direction," Young says. "You now have 28 teams and 45 men to a team. As a result, you have so many more players than before, and you're taking players from smaller schools whose programs aren't that sophisticated.

"So coaching staffs are doing a lot more teaching than ever before. And when there are so many teams using computers, spending all these hours going over tendencies, you want to get more expertise into your offense.

"The coaching staff can spend a lot more time analyzing situations than the quarterback can.

"Another trend is that there are more decisions a quarterback has to make after the snap of the ball. There are blitzes and coverages to pick up. People give you more looks, different fronts. You get teams substituting by situation. So a quarterback needs some help. It's a lot easier for the coaches sitting up there with pencils and notebooks. You're halving his job." c

Jerry Rhome, the offensive coordinator for the Seattle Seahawks, concurred.

"The defenses have gotten so much better, they're doing so many wild things, and you have to do wild things on offense," said Rhome, the man who coaches Zorn.

"There's just no way one guy can remember everything he has to remember out there," Rhome said. "And the way you win in this game is by adjusting. We can see it from the press box a lot easier then they can on the field.

"Our game Monday night against the Jets is a perfect example. We scored two touchdowns on them because of things we spotted upstairs to take advantage of what the Jets were doing. We never would have done that if the quarterback was calling the plays."

"Sure every quarterback would like to call his plays," says San Diego's Fouts, who does not.

"But every quarterback wants to win, too. I've got no objections to it. How can I? We're throwing the ball, we're winning games and we're having a great time. For me, it's the perfect situation."