Just guessing: the Atlantic Coast Conference 30-second clock and three-point line will make Virginia unbeatable next winter. Ralph Sampson will have a great time, at last free of clawing defenders who now must look out for the 19-foot jump shooters. And bet this: Ralph will score a couple of three-pointers himself.

Sampson unchained is only one happy prospect of the ACC move to a shot clock, because the clock will force coaches to play real basketball. Purists lament the need for a clock, but the need, alas, is real. To remember the Virginia-Carolina tournament championship game last March is to grow sleepy, very sleeeeeeeepy.

The irony is that everyone assumes the ACC shot clock is there to juice up offense. Scores will go higher. But the clock was made necessary by defenses. Too many coaches refused to play defense against ball-control teams; they ordered cautious zones.

They gave such orders because it is easier to wait 16 minutes and play pressure defense four minutes than it is to play good defense 20 minutes. They were content, pleased perhaps, to play these minigames with only a few significant plays. That way, they had fewer chances to lose.

This makes sense for coaches who know they can't coach good defense and/or know their players can't play it. So when a Dean Smith orders a delay to draw out the defense and create new offensive patterns, the easy thing for the other coach is to tell his guys: "Don't chase 'em now, don't give up any backdoors, just wait for 'em to play."

So we saw Virginia stand around on defense against Carolina in that championship game. Carolina wanted to run its delay. Virginia said it couldn't play defense against the delay. At this impasse, everybody just stood there. Two marvelous teams, with Ralph Sampson and James Worthy suited up, did nothing resembling basketball.

The 30-second clock should be put on the defense. If the defense doesn't go to man-to-man pressure within 30 seconds, make it a technical foul. One supposes this is an unwieldly idea, what with referees asked to define man-to-man pressure, but it would put the burden where it belongs--on coaches who seek the security of lazy zone defenses to avoid the risks of man-to-man pressure.

Instead, we get a clock that forces the offense to put up a shot within 30 seconds no matter if the team's best path to victory lies in patience and discretion.

The clock will be turned off the last four minutes of a game, so spread offenses in imitation of Smith's "four corners" will still be used (Phil Ford was so good at running the delay, Smith confessed last March, that he "almost felt guilty" about winning so often).

What we'll see, then, is a return to ACC basketball of the mid-'70s with scores such as 109-105.

Good.

It'll be fun again. For four seasons, the Sun Belt Conference has used a 45-second clock turned off the last four minutes. Commissioner Vic Bubas believes it a success that will spread. You wouldn't have known that from a March vote by members of the National Association of Basketball Coaches. Major college coaches voted, 391-1, against a 24-second clock. Of 1,542 voters at all levels, the vote was 4-1 against a 30-second clock.

Yet now the ACC coaches have voted, 7-1, for the 30-second version. And if the experiment succeeds, as it should for it will produce basketball where stall ball had been, the NCAA soon will make it law.

As for the three-point line, we should wait before applauding. The NBA finally saw the beauty of the three-pointer as practiced by the dear, departed American Basketball Association. And the Big Ten announced last month it would have a three-point shot.

The meaningful difference is in the distances. The pros use a line 22 feet from the hoop, measured into the corner, and 23 feet 9 inches above the key. The Big Ten proposes a 21-foot semicircle.

The ACC wants a 19-foot line. That is too close. It awards three points for too little skill.

The three-pointer should be a high-risk shot. Instead, the ACC proposes three points for a jumper made from inside the free throw circle. A 50 percent bonus from there will cheapen and distort the game.

John Wooden had an idea. If big men are ruining basketball, the Wizard said, the answer is not a three-point shot; give a team only one point for a tip-in. Oregon State Coach Ralph Miller says a three-pointer is foolishness "because you're rewarding a shoot-and-pray shot while giving only two points for a beautiful backdoor play."

Miller has an idea, too. "The last time I looked, colleges were still building more and more bigger arenas, more than in the pros. This is still a great sport. The only thing I'd like to see is for them to raise the cotton-pickin' rim."

Wouldn't raising the basket make it more of a big man's game?

"That's not so," Miller said. "The ball, because it's shot higher and necessarily with more force, bounces away farther. It doesn't hurt shooting percentages, either. At a high school camp once, we played 40 games with a rim 11 feet 3 inches high. In all but one game, the shooting percentage was higher than it had been at 10 feet."

Someday before Dean Smith retires, which is to say around the year 2000, we will see ACC basketball played with a 30-second clock, 11-foot rims, 23-foot three-pointers and basketballs painted red, white and blue. It will be wonderful.