Some things are predictable: Howard Cosell will have something to say; it won't snow Christmas Day in Washington, and the Dallas Cowboys will start playing their best when everyone else in the National Football League is preparing for their downfall.

Tom Landry's football machine has its gears meshed well enough to once again be the favorite to move out of the NFC playoff derby and into the Super Bowl extravaganza.

Remember the old Boston Celtics at the end of their dynasty? Well, Dallas is showing some of the same tendencies.

Like the NBA's Celtics, the Cowboys play just well enough early in a season to remain respectable, and just badly enough to create anxiety among their faithful. They always seem to be able to come up with enough extra effort when it matters.

Just as the Celtics would sometimes add a player to plug a hole, the Cowboys in midseason traded for John Dutton, a former unhappy Colt.

That was a major step for Dallas. This is an organization that prides itself on home-grown talent. But when Too Tall Jones left the flock, the Cowboys had little choice but to either acquire Dutton for two high draft choices or watch their playoff chances dim.

The Celtics also knew they always could rely on one player for a supreme performance in the time of their worst need. First Bill Russell and then John Havlicek carried this burden.

For Dallas, Roger Staubach is the man. Without him producing probably the finest season of his career, the Cowboys would be watching the playoffs on television Sunday instead of hosting the Los Angeles Rams.

A month ago, Dallas appeared vulnerable. Randy White was hurting, the Cowboys pass rush was horrible, Philadelphia and Washington were playing well and a three-game losing streak was adding worry lines to Landry's face.

The Cowboys still salvaged the East title.They took on the challengers and won, beating the Eagles in Philadelphia and the Redskins in Dallas.

Perhaps, as Washington's John Riggins believes, the fact that Dallas has become accustomed to performing well in important games saved the club this season.

Defensive end Harvey Martin has another theory to explain the Cowboys' success in the stretch drive.

"We had a goal," Martin said. "We had something to aim at. Early in the season, we just were playing to survive and hope we could win. For us, we need to be motivated, to have something to shoot for. Winning the East was enough, it got us going."

Now the Cowboys have a new goal: Super Bowl victory.

Dutton, a latecomer to all this Cowboy mystique, is fascinated by what he sees developing.

The Cowboys' surge began when Dutton became a starter at Jones' old spot. While he has not set the football world on fire since then, he has helped the Cowboy defense regain some of the stability it lost upon Jones' unexpected departure.

Larry Cole, who was playing end, now is at tackle next to Dutton and enjoying himself immensely. Cole is much better at this new spot, as he showed against the Redskins, while Dutton is a much more agile end.

"This is the first time we've had some stability on our line this season," said Ernie Stautner, defensive coordinator who has had to struggle with the pass rush since the start of training camp.

Yet Dutton has not emerged as a dominating player, as might be expected of a young, former Pro Bowler.

He says he still is "feeling my way, getting used to the teammates and to the way they play defense. It takes time and I feel more comfortable here every day."

Some player personnel people in the league, however, believe Dutton always had been overrated and that the Cowboys will find the price they paid for him too high.

But for now, Dallas has little room to complain. Dutton is filling a major void much better than any of the second line players and rookies Landry had available.

The question remains, however: just how good is this team?

If Martin is right, the Cowboys have been toying with the opposition and now will start to play more seriously in the playoffs

If others, like Riggins, are correct, the Cowboys may never get to Pasadena.

"Dallas is a regular team," Riggins said. "They are no longer the dominating force they were. They no longer have the mystique they had. People aren't afraid of them any more.

"I think they have won a lot of games in the past just because they were wearing Dallas uniforms. Put them in another uniform and the same team would have lost."

Los Angeles never has been able to beat that uniform in the playoffs. But Philadelphia has licked the Cowboys once in Dallas this season, and came close to sweeping the two-game series.