The coaches could be more in the spotlight than the players as the first round of the National Basketball Association playoffs begin tonight with games between the Atlanta Hawks and Boston Celtics at Boston Garden in the Eastern Conference, and the Denver Nuggets and Phoenix Suns at Veterans Coliseum in Phoenix in the West.

Wednesday, the Portland Trail Blazers visit the Seattle SuperSonics, in the other first-round Western Conference series, and the New York Knicks play the New Jersey Nets at the Meadowlands in the East.

Many of the Celtics are grumbling at the way Coach Bill Fitch is handling the team, which can only help the underdog Hawks. And Doug Moe in Denver is the best "noncoaching" coach around. He permits the Nuggets to run and gun and doesn't confuse them with things like set plays and tricky defenses. "Go with the flow," is the Moe motto.

Lenny Wilkens of Seattle may step down after the playoffs and wants to go out a winner. And Bill Blair in New Jersey, with only five games experience as head coach, tries to make his team forget Larry Brown and do things his way. Whether he has a job next year depends on how he succeeds. EASTERN CONFERENCE

Hawks-Celtics

The Celtics defeated the Hawks five times in six meetings during the regular season, but they have more disgruntled players than any other playoff team.

Boston has perhaps the deepest front line in the NBA, with Cedric Maxwell, Robert Parish and Larry Bird starting, and Kevin McHale, Scott Wedman and Rick Robey in reserve. In the back court, however, Tiny Archibald has been bothered by a hand injury and lost his starting job to Quinn Buckner. When Buckner sprained an ankle two weeks ago, Gerald Henderson moved into the lineup alongside Danny Ainge.

Knicks-Nets

This rivalry is one of the most intense in the NBA and, although the Nets won four of six meetings during the regular season, the Knicks may be too strong for them now. The departure of Brown has disrupted the Nets, who have no one who can stop Bernard King. New Jersey's Buck Williams should control the rebounding.

New Jersey is still trying to get the right combination in the back court; the Knicks have gone with the Rory Sparrow-Paul Westphal combination for the past few weeks. New York is the best defensive team in the NBA, yielding only 97.7 points a game; the Nets led the league in turnovers.

Western Conference

Nuggets-Suns

The Nuggets are fun to watch because of their loose style. They led the NBA in scoring with 123 points a game, and were last in defense--also averaging 123.

Phoenix, third in defense in the NBA, has been transformed from a finesse offensive team into a solid defensive squad led by Maurice Lucas and Dennis Johnson.

The Nuggets have the league's leading scorer, Alex English; he and Kiki Vandeweghe became only the third teammates in NBA history to score 2,000 each in the same season.

Blazers-Sonics

The SuperSonics opened the season with 12 victories and then faded, but came on strong at the end again.

David Thompson and Greg Kelser are the primary reasons for the late-season surge and Jack Sikma and Gus Williams have been dominant all year.

In midseason, Portland Coach Jack Ramsay moved center Mychal Thomson to power forward and Wayne Cooper from the bench to starting center and the Trail Blazers have been on a roll since.