The North American Soccer League used to be satisfied merely being mentioned btween talk about the beginning of the major league baseball season and the fading of the pro basketball and hockey seasons.

Now, with the opening of its 11th year this weekend, the NASL has cast aside its inferiority complex. The league is coming off its most successful season in attendance, 2.5 million, an average of 10,300 per game.It has an average of 10,300 per game. It has increased the number of games each team will play from 24 to 26 and broadened its TV coverage nationally.

The Cosmos (formerly New York Cosmos), featuring the incomparable Black Pearl, Pele, and the 1975 NASL champion Tampa Bay Rowdies, Minesota Kicks, Portland Timbers, Chicago Sting and the San Jose Earthquakes, are rated as the league powers on the strength of strong finishes last year and recent offseason acquisitions.

The division breakdowns and probable finishes in order of appearance: ATLANTIC CONFERENCE Eastern

The Cosmos (16-8 last season) lost the first half of their name but little else. The 36-year-old Pele, in his final NASL season, has slowed considerably but has no peer in field presence. Geiorgio Chinaglia, the league's leading scorer last year with 49 points, is probably the most exciting forward in the league. Goalkeeper Shep Messing and a recent signee' Yugoslavia mid-fielder (did they need him?) Vito Dimitrijevic, should help the Cosmos stay atop teh division.

Tampa Bay (18-6) had the best mark in the NASL a year ago and, despite losing half its famed "Murderers Row," Clyde Best and Stewart Scullion, and discontented goalie Arnold Mausser via trades, the Rowdies again will be strong. Forward Derek Smethurst, second in scoring (45), goalie Paul Hammond, English superstar Steve Wegerle and team fireball Rodney Marsh may be enough to earn Tampa Bay another crown.

The Washington Diplomats (14-10) may be one of the most improved teams in the league but, unfortunately, they are in the toughest division. Eric Martin ranks among the best in the net but Leroy DeLeon. Gary Darrell and recently acquired Peter Silverster may have to score often to offset a completely rebuilt defense.

The Fort Lauderdale Strikers (6-18), formerly the Miami Toros, picked up several good South African players to blend with holdovers Ronnie Sharp, David Proctor and goalie Gordon Banks. A .500 season may be asking too much. Northern Division

The Chicago Sting (15-9) has goalie Mervyn (The Magician) Cawston and a host of established veterans. The Northern Division defending champs have improved both defensively and offensively. Its "teen-age" trio, Miro Rys, Jimmy Kelly and John Lowey had fine rookie seasons and are loaded with enthusiasm.

Both the Connecticut Bicentennials (12-12) and the Rochester Lancers (13-11) have improved enough to give the Sting a run. A host of Portuguese players, including highly regarded Jaime Gracke and John Carlos, will join forces with defender Pete Chandler, forward John Coyne and goalie Gene DuChateau to give Connecticut (formerly Hartford) a strong squad.

The Lancers have an excellent scorer in Mike Stojanovic and a tough defense.

The Toronto Metros (15-9), the surprise league champion a year ago, may be in for a fall. Always a defense-oriented club, the Metros may find they may need a bit more this time around. They lost most of the offensive firepower they had in Eusebio and Wolfgang Sunholz to Las Vegas. Goalie Zelko Bilecki probably will be surrounded by 10 defenders and hope for tie-breaker games.

St. Louis (5-19) switches divisions but will have a tough time improving on its record, worst in the league last year. Several of the Stars were injured during the preseason and a rocky start is imminent. PACIFIC CONFERENCE Western Division

In its first season, Minnesot (15-9) won the division and reached the finals before losing to Toronto. Look for the Kicks, second in the league in attendance, to keep the turnstiles busy and opponents unhappy again. Paul Futcher joins brother Ron and Geoff Barnett should be more than enough to earn another division title.

Portland (8-16) should easily improve on its dismal mark of a year ago and, with a break here and there, could emerge as the division champion. The Timbers picked up strikers Clyde Best and Stewart Scullion from Tampa Bay and welcomed with open arms English stars goalie Graham Brown and forward Willie Anderson. Both European players were with the Timbers in 1975, 16-6 season.

The Vancouver Whitecaps (14-10) and the Seattle Sounders (14-10) will need help offensively if they expect to not only challenge for division honors but to match their records of a year ago.

The Whitecaps are sstrong defensively with Arnold Mausser and defenders Sam Laenarduzzi and Buzz Parsons, Seattle boasts the league's leading goalie in Tony Chursky. He will have enough to improve on his 135 saves, nine shutouts and only 20 goals allowed in 1,981 minutes if his team doesn't find someone to force play at he other end. The one plus mark is that Seattle led the league in attendance. Southern Division

As goes Ilija Mitic, so goes the San Jose Earthquakes (14-10). At least, that's the way it used to be. Fortunately the 36-year-old scorer (37 points) will have enough assistance this season to give the Quakes an edge in their division. Paul Child and Mike Liveric along with Mitic gives San Diego, 9-15), Dallas Tornado (13-11), Los Angeles Atzecs (12-12) and Team Hawaii (formerly San Antonio, 12-12) have picked up players in vital spots but still lack the ingredients to bring home a title.

Las Vegas has Eusebio and goalie Alan Mayer and little else. The Tornado picked up the college player of the year in Glen Myernick to go along with consistent goalie Ken Cooper. Georgie Best is still recuperating from a broken collarbone, but Steve David gives Los Angeles speed and scoring potential.Hawaii offers white sands, dancing girls and few victories.