Curtain-closing time for NFL regular season filled with uncertainties

Finding the overalls in Mrs. Murphy's chowder should be a snap this weekend, compared with what is still hanging on the National Football League's playoff clothesline with just one week left in the regular season. First, the positives. The Chicago Bears and the Buffalo Bills are both 12-3 and the only teams that have already locked up division titles - the NFC Central and AFC East, respectively. The significance for the Bears is that they have assured themselves of the home-field advantage throughout the playoffs.

Chicago coach Mike Ditka, whose team just did beat the Detroit Lions on Sunday, 13-12, might have both of his injured quarterbacks, Jim McMahon and Mike Tomczak, back in time for the playoffs.

The Minnesota Vikings, who were nipping at the Bears' heels in the division, now must beat Chicago to clinch a wild-card playoff berth. Minnesota had been coming on strong, especially on defense, in the last month or so. What appeared to be the NFL's best team, however, suffered a major embarrassment Sunday when the lowly Green Bay Packers beat them for the second time this season, 18-6. That win broke a seven-game losing streak for the Packers, who also stopped Minnesota in mid-October, 34-14.

Anybody who can explain that series should be the No. 1 draft choice this year by the United Nations.

Meanwhile, Buffalo still needs a victory over the Indianapolis Colts to clinch the home-field advantage throughout the AFC playoffs. The Bills, after consecutive losses to Cincinnati and Tampa Bay, got back on track with a 37-21 triumph over the Los Angeles Raiders.

The San Francisco 49ers and the Cincinnati Bengals, already assured of playoff berths, still hope to win their division titles. The 49ers can clinch the NFC West by beating the Los Angeles Rams on Sunday night in San Francisco.

Things would really get complicated in that division, though, if the Rams were to upset the 49ers. It would then be possible for L.A. to win division honors if Atlanta beat New Orleans. This would be based on the Rams having a better record (8-4) than the 49ers (7-5) against common opponents.

In the NFC East, the 10-5 Giants can own that division with a victory over the New York Jets, whose defense dates back to the Sieve Dynasty. But if the Giants somehow manage to lose and wind up in a tie with Philadelphia, the Eagles get the crown because they beat the Giants twice during the regular season.

In the AFC Central, Cincinnati can finish first if it stops Washington on Sunday, and could even claim the conference's home-field advantage in the playoffs were the Bills to lose to Indianapolis.

Even though Buffalo and Cincinnati would then have identical won-lost records, the Bengals get to play at home in the playoffs by virtue of an earlier win against the Bills.

Saving the worst for last, we come to the AFC West, which all season long has looked like a teen-ager's room that hasn't been bulldozed for 48 hours. While the Seattle Seahawks eliminated the Denver Broncos from the playoffs on Sunday, and the Los Angeles Raiders nearly eliminated themselves by losing to Buffalo, L.A. could still win the division.

It could happen if the Raiders beat the visiting Seahawks at the Coliseum. While this would then result in a three-way tie among Los Angeles, Seattle, and Denver (all with possible 8-8 records), the Raiders would be awarded the championship because of a 7-1 record within the division.

As for which teams might emerge from all this confusion and play in the Super Bowl on Jan. 22 in Miami, the answer probably lies in who plays the best defense. On that basis, the Bears and the Vikings would be early favorites from the NFC, and the Bengals and Bills from the AFC. Will 49ers keep Walsh?

Contrary to stories that still surface occasionally, Bill Walsh will be back with the San Francisco 49ers next season. Walsh will either return in his present capacity as the team's head coach or in a high-level front office position.

Asked recently by reporters about his situation, Walsh responded by quoting something he said former NFL coach Sid Gillman had once told him. Said Gillman: ``Once you've been in a job like yours for 10 years, people get tired of you. They look for things they can use against you. If you're not winning, they pick on that. If you are winning, they go after your personal life. People get bored easily, and when they do they want a change.'' Super no longer

Neither Washington nor Denver, last season's Super Bowl teams, has had much of a season. Hogtied by injuries, the Redskins (7-8) probably had their biggest breakdown on defense. The Broncos (also 7-8) felt that in Tony Dorsett they had acquired the running back needed to give the offense a dimension it didn't have during last January's 42-10 Super Bowl defeat to Washington. Dorsett, however, has not been particularly productive (617 yards, 3.6 a carry), and the team's star quarterback, John Elway, has had an off-year.