For several seasons, selecting the underdog at home provided one of the best ways to cover the point spread on NFL games. There was no need to ask questions. No thinking or research was required. You automatically played the underdog on its home grounds and you won, getting the points.

Then, last season, the underdog at home lost much of its attractiveness. The results weren't very thrilling this season, either -- until last weekend, when six of seven teams covered in that role. They were: Indianapolis, against Denver; San Diego, against Kansas City; Tampa Bay, against the Los Angeles Rams; Cincinnati, against the New York Giants; Philadelphia, against St. Louis, and the New York Jets, against Miami.

All except Indianapolis and Tampa Bay won straight up. The only underdog to lose at home last week was Houston, to Cleveland, 21-6. The Browns were favored by 2.

Another interesting statistic this year involving the underdog concerns Monday night games. There have been six Monday games, and the team getting the points has covered on all six occasions: Dallas, against Washington; Cleveland, against Pittsburgh; the Los Angeles Rams, at Seattle; Cincinnati, at Pittsburgh; Washington, against St. Louis, and the New York Jets, against Miami.

The six underdogs didn't just cover the points, they won outright. MONDAY NIGHT

All of which may or may not mean a thing in terms of this week. Certainly I wouldn't take Green Bay, getting 9 1/2 points in Chicago. No way. Not with the Bears being 6-0 and anxious to impress a national TV audience. Proceed at your own risk. GAME OF THE WEEK

Seattle at Denver. The Broncos are favored by 3 1/2. These teams share the AFC West lead with the Los Angeles Raiders. I'll take Denver. I don't miss many chances to go with Denver at home in an important game when the spread is in the field goal range. There's not a home-field advantage in the NFL higher than Mile High's.

The Broncos' defense continues to be one of the quickest in the league, always prepared, always likely to create two or three turnovers. Offensively, John Elway throws into heavy coverage much too often. Fortunately for the Broncos, their running game has improved faster than Elway the past two years.

Seattle should be playing better, but after Dave Krieg threw four interceptions at Kansas City, Coach Chuck Knox became a little gun-shy with his offense. He will have to open up more at Denver. That could backfire. Give the 3 1/2. OTHER PICKS

I'll also take the Giants, giving 2 1/2 at home against Washington; Pittsburgh, giving 4 at home to St. Louis; and Cleveland, getting 2 1/2 at home against the L.A. Raiders.

The Redskins' recovery from a poor start is not complete. In defeating St. Louis and Detroit they were able to dominate the opposition with their running game. They will not be able to do this against the Giants, and Washington has yet to establish its passing attack.

The Giants beat themselves the last two weeks with turnovers after getting off to a 3-1 mark. Allowing the Bengals 175 yards on returns Sunday was almost sinful. What's important is that the New York offense continues to develop nicely behind Phil Simms. This is a good team, much better balanced than it was in the past. I'm still confident they will make the playoffs. Give the 2 1/2.

The Steelers' problems at quarterback were brought into focus by Dallas' aggressive defense when David Woodley replaced Mark Malone in the second half. St. Louis does not apply that kind of pressure, however, and the Cardinals also are having trouble with their offensive front. Give the 4.

The number on the Cleveland game appears generous, with the Raiders having to rely on their defense to overcome a shaky quarterback situation. This figures to be a low-scoring contest, which makes getting points all the more attractive. Take the 2 1/2. THE LINE

Las Vegas' early week numbers had Kansas City favored by 1 over the L.A. Rams; Dallas by 4 at Philadelphia; Cincinnati by 4 at Houston; Buffalo by 1 over Indianapolis; New Orleans by 1 at Atlanta; the New York Jets by 2 at New England; Minnesota by 3 1/2 over San Diego; San Francisco by 10 at Detroit, and Miami by 13 over Tampa Bay.