SUPER BOWL XXIV : DENVER BRONCOS vs. SAN FRANCISCO 49ERS : Broncos Are Not Without Weapons : Football: Their hopes rest with NFL’s No. 1 defense and a big-play offense led by John Elway.

For reasons never satisfactorily explained, AFC teams dominated pro football in the ‘70s, when, nevertheless, the AFC’s Denver Broncos lost the 1978 Super Bowl game to an NFC power, the Dallas Cowboys.

In the ‘80s, things only got worse. That was a decade of NFC dominance--also for reasons unknown--and so in ’87 and ‘88, the Broncos lost two Super Bowls.

Now, worst of all, here come the San Francisco 49ers. With Joe Montana, Jerry Rice and Ronnie Lott--who are making a brief stop in Louisiana this week on their way to the Hall of Fame--the 49ers are being called an unbeatable terror.

What are the Broncos doing about it?

Here’s the anatomy of their response:

AT A GLANCE

As reconstructed by Coach Dan Reeves in the last six months, the Broncos now have two weapons that any other team would be proud of. Their defense was the NFL’s hardest to score on this season--yielding an average 14.1 points a week. And their offense has John Elway, perhaps the best athlete who ever played quarterback.

Two other assets are reliable kicking by a first-year specialist, David Treadwell, and a corps of big-play receivers.

Finally, Reeves is a decided asset in the area where every pro or college club needs it most.

“This is the best Denver team that I’ve been associated with,” runner-receiver Steve Sewell, a five-year veteran, said the other day.

It may not be enough. The national perception is that it won’t be nearly enough. But the Broncos are nothing if not optimistic.

“We’ll sneak up on them,” said owner Pat Bowlen. “I expect to win Super Bowls.”

In any case, his coach, Reeves, knows what he’s getting into. It will be Reeves’ eighth title-game appearance--as coach or player--the all-time record. By nightfall Sunday, remarkably, the Denver coach will have been in every third Super Bowl, on the average.

GROUND OFFENSE

For one of the few times in their modern history, the Broncos ran the ball successfully this season while featuring a rookie scatback, Bobby Humphrey.

This gave them offensive balance for a change. And by controlling the ball with Humphrey, a 1,151-yard rusher, the Broncos also stabilized their defense, promoting team balance.

On an Elway team, nothing could be sweeter.

It all came crashing down last week when Humphrey, in a minor collision with a Cleveland Brown, cracked two ribs.

Without him, Elway could beat Cleveland, but probably not San Francisco.

Almost surely, in a no-tomorrow game, Humphrey will try to play against the 49ers. The doctors could forbid it if they determine that more damage to a cracked rib might result in a punctured lung. But if pain is the only problem, most NFL teams mask it with a shot of medicine.

The question is how well a little running back could play in those circumstances.

Elway, minus Humphrey, would again figure as most of Denver’s running game himself--along with some support from Sewell, Sammy Winder and Melvin Bratton on draws, reverses and other odd plays.

The heavier, rebuilt offensive line is one unexpected Denver strength this season.

PASSING OFFENSE

Elway is a national phenomenon. He could throw the ball 50 yards, no doubt, while lying on his back. And put it in the hands of his favorite new receiver, Michael Young.

Even so, Elway had some trouble against NFC teams this season, when the New York Giants and Philadelphia Eagles both won in Denver. And he will be facing the best of all NFC teams Sunday--on the road, where, historically, it has been harder for him to win than it is in friendly Mile High Stadium.

One trouble area is the 49er secondary. Despite the class of Elway’s receivers--Vance Johnson, Mark Jackson, Young, Ricky Nattiel and runner-receivers Sewell and Ken Bell--they can expect to be largely neutralized by the 49ers’ clever cornerbacks and their all-pro center fielder, Ronnie Lott.

Thus the day’s main matchup could be Elway versus San Francisco’s front seven players, who have more mobility and generate a tougher pass rush than any seven-man group he has seen since Philadelphia in late October.

For most of the regular season, Elway was widely criticized in the mercurial Denver area. Then he was extravagantly praised after the Broncos beat an AFC team last week. They only have eyes for Elway in the Rockies, where, this time, he is sure to be the one blamed if the team loses again--even though the real cause is Denver’s talent shortfall by comparison with San Francisco’s.

Most likely, this will be another day that Elway spends tearing around behind the line; occasionally venturing downfield; looking for a crack in the defense; aiming to make big plays; and proving, once more, that a football field is the wrong stage for a one-man band.

DEFENSE

These are the definitive things about Reeves’ new defense:

--With nearly unprecedented success, he and a new coordinator, Wade Phillips, have in one year’s time totally changed the club’s philosophy--and much of the personnel--while driving the Broncos into the Super Bowl with a team that led the league this season in fewest points allowed.

--There are no dominant players in the front seven. The most famous, linebacker Karl Mecklenburg, is no Lawrence Taylor, and the Bronco pass rush isn’t much. What Phillips has effectively changed is Denver’s defensive approach, which used to be passive. It now exudes aggressiveness and togetherness, incorporating the notions of the last two coaches he worked for, his father, Bum, and Buddy Ryan.

--Opponents keep saying that Denver’s cornerbacks, Tyrone Braxton, Wymon Henderson and the others in the nickel packages, can be beaten.

--The strength of the defense is at safety with rookie hitter Steve Atwater and veteran hitter Dennis Smith, who both play like 49er Ronnie Lott.

The problem for Denver this week is the scope and variety of the 49er offense, which rendered Minnesota and the Rams helpless. In coaches’ language, you have to play the 49ers honest. That is, you can’t load up the defense in any one area because they’re so strong in all areas.

What’s more, the pass rush never knows exactly where to find Montana--he’s like quicksilver--or where he’s going next. And much the same is true of other 49ers.

The Broncos, however, have agreed to play. They’ll give it a try.