Undated (AP) _ How about, just for fun, we assemble an NBA All-Star team, sort of a fantasy team to compete in the playoffs?

At center we'll use Akeem Olajuwon with Moses Malone behind him. The guards can be Magic Johnson and Michael Jordan, with Isiah Thomas and Clyde Drexler coming off the bench. The forwards will be Charles Barkley and Karl Malone, with James Worthy and Dominique Wilkins backing them up.

Like the looks of our club? There are two common threads running through the roster. Besides being composed of some of the best players in the NBA, the squad includes only players who came out early, declaring for the draft and turning pro before completing the prescribed four years of college ball. In Moses Malone's case, it was before completing any years of college ball because he came straight to the pros from high school.

But for every Akeem and Magic, there's a Kenny Drummond and Russell Pierre, teammates at North Carolina State, who both declared in 1987 and who both were not drafted. For every Jordan and Malone, there's a Dwayne Lewis and Kevin Smith, who said to the NBA, ''Here we are,'' and were told, ''No thanks,'' by the pros.

The deadline for undergraduates to file for the June 27 draft was midnight Saturday, and at least two of the top college players - junior J.R. Reid of North Carolina and sophomore Jay Edwards of Indiana - said their names would be included. Junior Derrick Coleman of Syracuse, who had been expected to declare for the draft, decided instead to stay in school for his final year.

''I'm a little nervous,'' Reid said. ''It's a big step for me. I had a lot of fun here (at North Carolina). Now, I think, is a good time for me to go on. I think the situation in the NBA, and the money situation, made it a good time for me to come out.''

Coleman went the other way, saying, ''I talked to my teammates, my coaches, my friends and my family and I feel it is in my best interest to stay at Syracuse.''

''It's a very personal, very private decision,'' said Rod Thorn, the NBA's vice president of operations. ''It's hard for an outsider to judge. Sometimes, you look at a kid who comes out and you say, 'My goodness, what is he doing?' But unless you know the situation, it's hard to judge.''

Thorn brings a thorough perspective to the issue, having been a player, coach, general manager and now league official.

''By and large, I think it's best for a player to stay for the full four years in college,'' he said. ''The experience and maturity that can provide is so important. When a kid is 17 or 18, he's growing and changing. To be rushed into a pro situation, and make him go against great players every night, I don't know if that's a good thing to do.

''I do think, though, there are cases when a player has no interest in school, is unhappy with his coach or whatever and does have the ability to play in the pros. They might be better off to declare.''

The classic cases - perhaps the two most dramatic extremes - of players declaring early are Bill Willoughby and Moses Malone. Both went to the pros straight out of high school, Malone in 1974, Willoughby a year later.

''Willoughby was thought of as a great, great, great player,'' Thorn said. ''But he never fulfilled the promise he showed coming out of high school. If he had matriculated at a university, who knows how good he might have been.

''Moses, on the other hand, was ready.''

Willoughby drifted through the league for eight years, playing just 488 games for six teams and averaging a distinctly average six points per game. Malone just completed his 15th professional season and has been an NBA All- Star every year since 1978.

In the days when Malone and Willoughby turned pro, undergrads were ushered into the pros via a ''hardship'' draft. That term was dropped in 1976, when, following lengthy court battles, the league and the players association agreed that a player's financial situation should not affect his eligibility for the draft.

Other sports have different regulations for draft eligibility.

The NFL generally requires that a player's college class have graduated, but makes exceptions, such as the one granted Heisman Trophy winner Barry Sanders last month. Twenty-five players filed for special eligibility in this year's draft and each was allowed in. Only 12, however, were selected.

In hockey, draft eligibility is determined by age. A player must be 18 to be picked on any round and no older than 21 to be selected in the first three rounds. There are also experience requirements, either in Canadian junior hockey or in United States high school or college hockey.

Baseball has separate rules for high school and college players. Generally, the baseball draft is open to graduating high school seniors or college players who are 21, have completed their junior year, completed eligibility or left school.

NBA superscout Marty Blake has strong opinions on players declaring early for the draft. ''I don't agree with anybody coming out early, except in mitigating circumstances,'' Blake said.

Mitigating circumstances, he said, is having the kind of talent of a Michael Jordan.

''A few will come out every year,'' Blake said. ''Some who do are players with the ability to play in the NBA, who will play in the NBA anyway. But I don't think the majority are ready as undergraduates.''

Blake makes it a practice not to discuss undergraduate prospects. ''I know a few who might come out who you never heard of,'' he said. ''And you won't hear of them again.''

He recalled a conversation last year with the father of a marginal college player, who phoned him for advice.

''He said, 'We're thinking of declaring,' '' Blake said.

The scout thought for a moment about the player and his talent and then answered the father.

''I said to him, 'Declaring for what?'