The National Basketball Association starts its thirtieth season on Friday, but all indications are that the league is behaving like a spoiled teenager rather than showing the maturity of middle age.

The league with the highest payrolls, the most balance, and ultimately the most talent of any of the major professional sports has become the biggest enigma as its status in the sportsworld has risen.

Lately even the most hard-core sports fan cannot deal with the change in tempo and temperament in the NBA, and who can blame him? Defense is a lost art. The average salary is over $120,000 (and that includes the likes of Kevin Stacom). Physical play is a watchword and "muscle tussles" are common sights.

The events of the past six months have not helped things. John Havlicek retired, and in so doing, stripped away the last vestiges of a classier era. Bill Walton uncovered Nixonesque medical practices in Portland and was brave enough to make them public. And in case you forgot, the Washington Bullets defeated the Seattle Supersonics with a best-forgotten cast of characters for the league championship.

Rick Barry took off for Houston. Bobby Jones and George McGinnis swapped teams. Marvin Webster brought his eraser act to New York. Walton played drums for the Grateful Dead at a concert in Egypt. Buffalo became San Diego. John Y. Brown became the Celtics. Earl Monroe and Truck Robinson became holdouts.

They disallowed hand-checking on defense, experimented with a three-point field goal, added another referee, and tightened up rules on zone defenses. And Jesus, though they tried, the Nets were still bankrupt and Marvin Barnes only played when he felt like it.

So life begins and life goes on in the NBA. It promises everything and promises nothing. The stars are there as always, but they realize now that the pay is good, the stage all theirs, and The Fans something that meant more during college.

Welcome to the world of big business, realizes the kid who thought Elgin Baylor and the Big O would always be there for his personal enjoyment. And for that matter, welcome to the 1978-79 edition of the NBA. Watch your step...

Atlantic: The champion Bullets move over to this division, but will be lucky to grab second place at the season's end. Philadelphia virtually locked up the championship with the Jones for McGinnis swap, provided Julius Erving can still do it, ABA-style. The Knicks are good on paper, and will be good if the paper is legal tender and given to Monroe and Jim McMillian. The Celtics will reach .500 only if opposing teams refuse to play while Dave Cowens is out. With Kevin Porter traded to Detroit for Eric Money, the Nets need a play maker who can bounce the ball as well as they bounce checks.

Central: The Rockets may have helped themselves to the division title with the acquisition of Barry, the return of Rudy Tomjanovich, and the added playing time for guard Mike Newlin. The Spurs have awesome fans and a starting lineup to match, led by scoring champ George Gervin, but a weak bench could kill them in the stretch. Coach Bill Fitch has his Cavaliers looking steadier than ever, and that means playoffs and not much more. As for the Atlanta Hawks, a backcourt of Charlie Criss (5'7") and all American Butch Lee looks like fun, but who said this game was fun? The Jazz looks flat without Truck Robinson. The Pistons have gone back to being terrible for a living.

Midwest: The Denver Nuggets' shooting gallery of McGinnis, David Thompson, Dan Issel, and new flinger Charlie Scott should outscore and outlast the other entries of the league's weakest division. The Bulls have no superstars, an aging Norm Van Lier, and a new coach in Larry Costello. The Bucks are a year and a center other than Kent Benson away from winning it all. Indiana lost two of its best players (Dan Roundfield and Earl Tatum), leaving none. The Kings finally have all American Phil Ford under contract. Not bad for the worst team in the league.

Pacific: Kareem Abdul-Jabbar is great whenever he wants to be, a characteristic he holds in common with the extremely talented Los Angeles Laker team. If the Lakers decide to sit back and sun-bathe the season away either Portland (with or without a truckin' Bill Walton), Phoenix (with a healthy Alvan Adams), or Golden State (with the league's best backcourt in Phil Smith and Barry-compensation John Lucas) will win the street fight for king of the West. Seattle is going nowhere without Marvin Webster. San Diego already went somewhere, but the Clippers are still Buffalo to those of us who know and pity them.

So sit back, and if you don't like what you see, remember that you can't expect much from a league in which Sidney Wicks and Brent Musburger earn their living.