Hubie Brown, the Atlanta Hawks' coach, took a reporter's notebook and drew on it a facsimile of the free-throw lane.Then he drew in "the box," which is a spot next to the lane about three feet from the basket.

"On Sunday, Elvin kept getting the ball in the box," said Brown. "It was aggravating. Nobody gets the ball on us in there."

So Brown did something about it two nights ago and he drew a picture of his brainchild on the reporter's notebook. An "X" represented the Bullets' main man, Elvin Hayes, and dotted lines showed the paths passes took. Then Brown drew a semicircular line that began behind Hayes' "X" and curled around in front of it.

Done in ink on scratch paper, it was a portrait of a memorable Atlanta victory.

The semicircular line meant that an Atlanta player had moved from behind Hayes to in front of him. No longer could the Bullets make a simple, direct pass to Hayes in the box. No longer could Hayes get the ball so close to the basket that he was unstoppable. If he wanted the ball, he had to leave the box. If the Hawks were to lose, they would lose with Hayes scoring from long distances not at point-blank range.

After scoring 31 points in the first game of the Bullets-Hawks playoff series, Hayes made only five of 17 shots in the second game. As marvelous as Bobby Dandridge is, he can't beat respectable teams without Hayes' scoring help. They scored 61 points in the Bullets' 103-89 first-game victory, but had 46 (only 10 by Hayes) in the Hawks' 107-99 second-game victory.

"Now, will it work for the rest of the series?" Brown said of the Hayes stratagem. "I don't know."

Probably not.

Hayes is too good to be beaten again by the likes of the men Atlanta used against him two nights ago. Unless he plays terribly again, Hayes will get his normal 20-25 points against the Hawks' Tom McMillen and Steve Hawes, who are earnest but heavy-footed big men.

Whatever happens, it is going to be fun. A week ago, the Bullets fretted about playing Houston in this series. They worried about Houston's great shooters and Moses Malone's board work. Given a choice, the Bullets preferred to play Atlanta. And when the Hawks surprisingly whipped Hoston in two straight miniseries games, the Bullets had their wish: Atlanta in the playoffs' second round.

One of the problems of wishing for something is that somethings you get it. The Hawks may be exactly what the Bullets can't handle. No one has has ever mistaken Elvin Hayes for a passer, and if Hayes doesn't pass against Atlanta-with two and three men leaving someone open to come guard Hayes-then the Bullets are in big trouble. Houston doesn't play defense the way Atlanta does.

Almost no one plays defense the way the Hawks do. That's because only the Hawks have Hubie Brown coaching them. He screams, cajoles, flatters, threatens, demands, praises. During games, he will turn his back on the action to explain to his men on the bench what just happened on court. He is a teacher. Give me $10 million, sell me a pro basketball team and the first thing I'll do is hire this screaming teaching to coach it.

With the Kentucky Colonels of the late American Basketball Association, Hubie Brown, 46, a coach half his life, transformed Artis Gilmore from an awkward, stonehanded statue into an effective, even mighty, offensive machine. That was brown's first pro job and in his first year he won the ABA championship.

But he quit after the second year in Kentucky. The owner, John Y. Brown Jr., fancied himself a savior of pro basketball. He would teach these greedy pros a lesson.He sold Dan Isel for $600,000, and at that moment the franchise was doomed. Without Isel, Kentury fell to fourth in its ABA division, and Hubie Brown quit to go to Atlanta-shortly before John Brown folded the Kentucky franchise.

At Atlanta, Hubie Brown has worked wonders. The owner there, Ted Turner, was losing so much money with his baseball team, the Braves, that he instituted a shoestring budget for basketball. At one point, the Hawks' entire player payroll was $800,000-which is what Denver pays one man, David Thomspon.

With a ragtag collection of people no one else wnated-Brown took on a 5-foot-8 guard, Charlie Criss, and took McMillen when Buffalo and New York gave up on him-Brown has steadily built the Hawks to respectability. They won 31 games his first season, 41 last year and 46 thiss. When they beat Hoston in the miniseries last week, it was the Hawks' first playoff victory in six years.

And now the Hawkes have beaten the defending world champions on the champs' home court to tie the series at 1-1. What might have been a dull series will be fun, indeed.

If the best-of-seven series goes the full route, three of the last five games will be played in Atlanta's Omni, where the Hawks had the league's best home-court record (34-7) and have won 17 straight games.

"The noise at the Omni is incredible," Brown said. "Whether we have 4,000 people there or 16,000, it is awesome. We have the fourth-lowest budget in the league. Our average experience is 1.7 years, maybe the youngest team in the league's 35 years. And the people are responding to the fact these guys are working hard. They see them pressing and trapping and playing defense all night."

Not that brown expects the Bullets to pay any attention to that home court record or the noisy love affair Atlanta has with its bargain-basement team.

"We know that when the Bullets come into the Omni, they're going to play their hearts out," he said. "They're champions. It will be great basketball."