Shortly before midnight Saturday, Buck Williams turned Maryland's basketball team into a pumpkin. By deciding to pursue postgraduate work in rebounding instead of his senior year in college, Williams has caused the sort of high-altitude spinout only risk-loving rocket jockeys usually experience. All of a sudden, the Terrapins are plummeting toward becoming . . . would you believe the George Tech of the north?

No.

Still, unless Lefty Driesell can sign one or two skywalkers with vise grips for hands, or shows us some genius-level coaching, or maybe both, Maryland will be spectacularly ordinary next season. Its realistic goal last year was the national championship; its realistic goal this year might well be an NIT bid.

With Albert King, Greg Manning and Ernest Graham gone, there were precious few gifted players available to Driesell, ones comfortable with a basketball at the highest level of competition. Without Williams, Driesell now has almost no one to get the ball to them.

We're moving ahead too quickly here, of course, making too many assumptions, asking lots of questions except the essential one today. Which is: was Buck Williams' decision to turn pro the right one?

Absolutely.

This is not to undervalue college life or a college diploma. Undoubtedly, Williams would be better off in many ways, academically and athletically, with one more year at Maryland and his degree. But his value in his chosen profession probably will not be higher than it is now.

The NBA wants him badly.

Alone, Williams is not a franchise. He is neither tall enough nor shoots well enough to have a Kareem- or Walton-like impact on his new team. He is not flashy enough to pay for himself instantly, to cause an extraordinary rush for season tickets.

What he is, unselfish, tough and unrelenting, might be the scarcest quality in the NBA, if not in all team sports. Williams never will make us forget the Doctor or some others born to invent moves in midair or to take the game to another, once-unimagined plateau. He will make us remember Paul Silas and Wes Unseld, that breed of quiet class without which no team becomes a champion.

The understandable bleats of Driesell and Terrapin fans to the contrary, Williams is leaving Maryland at exactly the right moment -- for Williams. Some of us have been privately insisting he should to now, but reluctant to shout it in public for the obvious implications about Driesell. The poor left-hander has been kicked enough this year.

Perhaps Williams saw the same realities. If he seemed to be wearing hobbles at times this season, what with all the defensive gimmickry thrown at him and King at the most critical moments, he might suffocate next season. It is not too much of an exaggeration to imagine one defender inside his jersey, another planted on his feet and still another perched atop his shoulder.

Buck and the fawns, we might have called Maryland's team. The other special players, we were told, would be the freshmen, though Jeff Adkins did not seem anywhere near as wonderful as advertised during the Capital Classic and Adrian Branch might drive Driesell goofy before Duke or Wake.

So Williams could see every coach on Maryland's schedule doodling defenses to make the Buck stop here -- either 15 feet from the basket with the ball or five feet from the basket without it. Both ways he is reasonably harmless. With a jump shot he can trust beyond the length of his shadow, Williams would be a pro all-star for the '80s.

He is a natural forward, but dominated centers when Maryland needed that the last two seasons. Except for a time or two against Ralph Sampson, and even then Williams -- or his team -- won the rematch. Sampson's staying at Virginia is another good reason for Williams to leave Maryland.

There should be no hint of cowardice read into that. Williams showed his courage against Virginia in Charlottesville this season. Sampson blocked shot after shot after shot by Williams -- but Williams still kept testing him. And all but made him disappear in the ACC tournament semifinals. A 6-8 player played taller than one 7-4 that night.

But the reality of basketball is that a Sampson always gets picked before a Williams, on the playground or in the NBA draft, by a Bob Ferry or some ferryboat operator. Which means that for Williams to get the maximum pro money available he should turn pro the year Sampson does not.

Very likely, Williams was more anxious than the rest of us over Sampson's decision. He made his own, or at least made it public, several hours after Sampson's. The logic of such as the Dallas Mavericks is reasonable enough. If you can't get a Rolls, a Mercedes isn't bad.

Unlike what might happen to Williams, Sampson will not decline in value next season, even though his team might lose more regularly. Probably, North Carolina has passed the Cavaliers in the ACC already. And everyone else will build fences of guards and centers around Ralph that might make him seem to be drifting backward, toward mortality.

The pros are smarter. On Super Bowl Sunday, the brains of a coach named Eldon Miller turned even mushier than usual and scouts got a unique glimpse at Sampson's potential to dominate. Miller allowed his Ohio State team to play honest, one-on-one defense against Virginia. Sampson looked like the most destructive force ever dropped on a basketball floor.

That is what the pros will remember, the day a very good center (Herb Williams) tried to play Sampson alone and got demolished, the day Sampson moved inside and outside with almost equal ease, the day he made one indelible move that convinced us a forward might be ready to pop out of that 7-4 frame.

Barring serious injury, Sampson will be the No. 1 NBA draft choice whenever he chooses to turn pro and regardless of how his team performs. That is not quite true for Williams. Being smaller, slightly less dominant, he can be even more frustrated by college defenses and the shims of pro scouts.

How might they remember Williams next year? As one of the best combinations of rebounding and scoring in all of basketball, when he had players that often forced defenses away from him? Or as a player whose numbers slipped drastically trying to carry a team himself?

Wisely, Williams chose not to allow them that final question.