Because no team has gone to the Super Bowl twice in the last four years, because two recent Super Bowl losers and last year's winner have fallen so swiftly and so far from glory, idle minds are pondering the Death of the Dynasty.

For every decade there has been one supreme team: the Chicago Bears in the 1940s, the Cleveland Browns in the '50s, the Green Bay Packers in the '60s and the Pittsburgh Steelers in the '70s. Will there be such a force for the '80s? Or have the preachers of parity found a way to keep genius from running rampant?

Hero today; burned out tomorrow.

The Los Angeles Rams and the Philadelphia Eagles carried the NFC banner into the Super Bowl after the '79 and '80 seasons; the San Francisco 49ers won the game last year. With legitimate protest from just one precinct, Chicago, those three were the worst teams in the conference this season.

The valleys are following the peaks so suddenly that a savvy coach had better start looking at another line of work an instant or so after being judged best in his profession. Coach of the year isn't an honor any more; it's an anchor.

"Don't think you'll be seeing any more dominant teams," said the Miami Dolphins' Don Shula. "Too many things working against that. More brighter coaches and organizations in the league than ever."

Don't think you'll be seeing Shula shying away from trying to fill that void of sustained excellence. And if quarterback David Woodley matures as rapidly as Shula hopes, the Dolphins have a fine chance to be very good for very long. They are quite young at several positions.

Some other teams are as obsessed.

The New York Jets have enough quality players at the right positions to be contenders for several years; the Atlanta Falcons need more discipline; the Minnesota Vikings need defensive backs.

The poor Cincinnati Bengals seem to have everything, yet not quite enough at one or two climactic moments each year. This draft Don Coryell surely will devote to finding some linebackers for the San Diego Chargers, linebackers who don't look like safeties. He also is likely to demand that Louie Kelcher be more active than a beached whale.

A longshot team for the future? The league's most consistently awful one since its formation: the New Orleans Saints. They have been doing unsaintly damage on defense lately and have a young quarterback with enormous ability in Dave Wilson.

"We're a fullback and a tight end away from being very, very good," an official predicted.

Ordinarily, that would be taken as seriously as a Defense Department aide declaring the country is two hand grenades away from weapons parity with the Soviets. But Bum Phillips has a way of being able to win grandly in a hurry.

Also, based on this season, the Saints are in the weakest division in the league, the NFC West.

That's this season. This Garvey-ed, Donlan-ed, homogenized season that didn't deserve to have the two best teams in each conference in the Super Bowl.

Next season?

The assumption is that each of the teams, the Redskins and Dolphins, that made it here is capable of returning to the Super Bowl. That's the reasoning almost every year. Lately, it's almost always been wrong.

If the Saints are competitive, everyone else surely is. Even the Baltimore Colts. Especially the Colts with two more drafts.

Dynasty building demands a massive foundation that floats. The idea is for the strength of a team to vary depending on how quickly the human parts wear out. That requires almost flawless use of the NFL's prime tool, the draft, and an extraordinary amount of luck before and during important games.

The Steelers had it all in the '70s. They were so consistently splendid scouting that they got Lynn Swann and John Stallworth on the same draft. For years, their top four or five picks not only made the team but made significant contributions.

The Dolphins had it going until the World Football League lured away Larry Csonka, Jim Kiick and Paul Warfield in 1974, the year after they had won back-to-back Super Bowls. With those three players, Miami might well have be in at least one or two more.

The U.S. Football League might do what the WFL did: dilute the talent just enough to keep blossoming teams from reaching full bloom.

Until the recent surge of new teams, the Super Bowl was getting to be a very private affair. Even with the rise of Los Angeles and Philadelphia, San Francisco, Cincinnati and Denver in the last five years, nearly half the league's 28 franchises never have qualified.

No St. Louis Cardinals, for instance. No Detroit Lions or New York Giants or Chicago Bears, to mention three historically rich teams gone sour.

In 17 years, only 15 teams have played in the Super Bowl.

"Dallas practically owns the thing," said the director of the Elias Sports Bureau, Seymour Siwoff.

That hits the dynasty-decline theory the way Dexter Manley smacked Danny White last week. Yep, Dallas has been in the Super Bowl five times and in the NFC title game four times in the last six years. Grudgingly, nearly everyone admits the Cowboys still are Yankee-like, still the team it is most satisfying to beat.

Always being contenders may be as close to dynastic as the NFL allows any more.