The quarterfinal round of the North American Soccer League playoffs provided more ammunition for foes of the current playoff system.

The idea of a two-game series was never popular with most clubs, because it virtually wiped out any home-field advantage the better teams might be entitled to as a result of the regular season.

The fact has been borne out over the last two years. Six of eight underdogs have won quarterfinal series by taking advantage of home openers to gain momentum and then win the series on the road.

Most clubs would like to see all rounds decided in one game or three games.

"Who ever heard of a two-game series?" one official of the Diplomats asked. "Either they play one game or three games. Or if they insist on playing two, they should decide the series on goal differential."

That system would have made it all but impossible for the Cosmos to recover from their 9-2 opening loss to the Minnesota Kicks.

If the Cosmos had been eliminated, there would have been many unhappy ticket holders for the Soccer Bowl, scheduled Aug. 27 at Giants Stadium.

The game is a virtual sellout mainly because New York-area fans, confident the Cosmos would be playing in the game, bought most of the 77,000 tickets.

The semifinal matchups now pit the Cosmos against Portland - upset winners over Vancouver and Fort Lauderdale and Tampa Bay in an all-Florida war.

The Cosmos can be had, but probably won't be in a series likely to go into the minigame after the teams trade wins on their home fields.

It is predicted here that Fort Lauderdale would knock off Detroit, so the prediction in the Tampa Bay series will stay the same: the Strikers in an upset.

The announcement that the Colorado Caribous, whose total attendance was a little better than what the Denver Broncos draw for one game, will move to Atlanta, was no suprise to league observers.

Commissioner Phil Woosnam has wanted a club in Atlanta ever ince the Chiefs for whom he served as coach and general manager, folded in 1973. The new club will also be called Chiefs.

The possible shift of the Memphis Rogues in Shea Stadium under the ownership of Gulf-Western (Madison Square Garden) is still a possibility, but not likely this year.

The holdup is the Cosmos, who want a huge indemnity fee for the invasion of New York, somewhere n the neighborhood of $7 million. Another possible franchise shift: Oakland to St. Louis. Anheuser-Busch is reportedly interested.

Although Coach Gordon Bradley is in Florida resting for a few days, the Washington Diplomats' offseason scouting work is already under way.

Bradley's assistant coach, Joe Mallett, flew to London Thursday and saw his first game of the English League season last night. Mallett will make an extensive scouting tour of Europe before returning here.

The Dips have three major needs in Bradley's mind: a big strong striker, midfielders of any size as long as they can play, and a sweeper not prone to fouls and yellow cards. The Portland playoff game provided textbook proof of the Dips' weaknesses in these areas.

The Dips and the league are currently planning an indoor season that would include 18 teams. The big question for Washington is - where will the club play?

Bet on Capital Centre. The Dips learned the hard way last winter that they cannot draw in the D.C. Armory. Besides their relationship with Armory management was less than ideal.

Thus, they will probably accept whatever terms Abe Pollin and Co. dictate for rent. A telltale clue: the team has already sold the boards it used in the Armory last year . . . Only other place in the area with boards? You guessed it.