For the second consecutive year on draft day, the Washington Bullets were among the most daring and innovative teams in the National Basketball Association yesterday.

They traded starting forward Greg Ballard and reserve center Rick Mahorn, acquired veteran forward Dan Roundfield, selected Wake Forest forward Kenny Green with their first-round pick and surprised the league by selecting Manute Bol, a 7-foot-6, 190-pound center from Sudan, on the second round.

The day started just after midnight with the trade of Ballard to the Golden State Warriors for the second-round choice the Bullets would use to conscript Bol, a player considered a long-term project after playing one season at the University of Bridgeport. Washington also got a second-round 1987 pick in that deal. For the short term, the Bullets gave up Mahorn to the Detroit Pistons for Roundfield, who is 32. And they selected Green with the 12th pick of the first round.

The selections came after the New York Knicks opened the draft by making official their claim on Georgetown center Patrick Ewing, a move that helped spur the Bullets into action. "Everything is based on competition. We're in a very competitive division," said Washington Coach Gene Shue. "You always have to aggressively look to improve. You can't stand still, because teams will move right by you."

General Manager Bob Ferry said his team now has players with "star quality" at each position.

The Bullets envision a starting five of Roundfield, Jeff Ruland and Cliff Robinson in the front court and Gus Williams and Jeff Malone at guard. They are pleased by the flexibility that group should give them. Williams and Robinson arrived in flashy trades on draft day 1984.

Robinson and Roundfield, both 6-9, have exhibited strong rebounding ability, as has Ruland. All three are also among the quickest players in the league at their positions. And Shue is hoping Green will add an instinctive approach to offense.

"He plays offense easier than the people we have now," Shue said. "We have guys who need plays to get their shots off, but sometimes, late in the game or in a playoff situation, you can't always do that.

"You need a guy on offense who you can give the ball to and he'll take it where he wants to and score. That's what Green can do. He has a very quick release, he gets the ball and shoots it. In that sense he's sort of like a Bernard King or Mark Aguirre."

Green, who entered the draft a year early, averaged 17 points and eight rebounds as a junior last season. Now listed at 6-7, he played in the pivot much of the time at only 6-6. The second-team all-Atlantic Coast Conference player raised his draft stock with a strong performance at the NBA's predraft camp for collegiate players in Chicago this month.

"I always felt I was a good player but that showed more of what I could do," Green said in a telephone interview. "I was able to play my natural position and show that I could handle the basketball and do other things."

Such opportunities were limited during his three years with the Demon Deacons, a factor Green said led to his entering the 1985 draft.

"I would've been happy staying in school for my senior year," he said. "I think it would have helped me in the draft next year, too. But I had to do what was best for me. I played on some great teams but I wasn't able to do what I wanted to do. I wasn't too fond of playing center at 6-6, especially in the ACC. It was just a frustrating year."

The selection of Green drew some boos from the 1,500 or so fans in attendance at Capital Centre for a broadcast of the draft; the announcement of Bol's selection was met with a mixture of cheers and laughter.

A Division II all-America last season, Bol averaged 22.5 points, 13.5 rebounds and 7.5 blocked shots a game at Bridgeport.

Bol was expected to be taken before the Bullets' first choice in the second round, No. 31 overall. When that didn't happen, Ferry didn't hesitate in the chance to add to his reputation as one of the NBA's biggest risk takers.

"His legs aren't any bigger than my arms and I'm not exactly Steve Reeves or Lou Ferrigno," said Ferry, who stands 6-8 and weighs substantially more than Bol. "He is just absolutely unique and can do incredible things. He catches the ball off the rim and dunks it flatfooted and he does it with grace. If he can make it in the league, he has the potential to be the best shot blocker in the history of basketball."

How long that will take is the big question. Although Ferry claimed that Bol is 21, others have said he may be as old as 28. The sports information office at Bridgeport could only place his age at "somewhere between 21 and 27." It also said Bol reportedly is up to 199 pounds, although he is listed as 190.

The logical step in Bol's development is probably to place him with a team in Europe, where he would get to play every day. According to Shue, that might be the second step. "First, we're going to feed him," he said.

Bol is currently playing with the Rhode Island Gulls of the United States Basketball League. If he does not play in the NBA, the Bullets would retain his rights. If another team wanted him, it would have to make a deal with the Bullets.

The Bullets also gave up yesterday on Mike Gibson, who played for the team in 1983-84 and in Europe last season. The Pistons acquired Gibson's rights in the Mahorn-Roundfield deal. Washington took Gibson in the second round of the 1982 draft and the 6-10 forward from South Carolina-Spartanburg played a single season with the team, averaging 1.7 points in 32 games.

Roundfield averaged 10.9 points and 8.1 rebounds in 56 games with Detroit last season, his 10th in the pros. The former Atlanta Hawk missed 26 games because of injury, including 20 because of arthroscopic surgery on his left knee.

Roundfield was a fixture on the NBA's All-Defensive team between 1980 and '84. His age and the condition of his knees obviously made him expendable to Detroit, but Shue said he was delighted to have him.

"As long as he's performing, he'll be able to play as long as he wants to," Shue said. "We are missing some bulk but we saw an opportunity to get a player that could start for us and I think we've improved that spot. I think we're better offensively and defensively."

Roundfield was not available to comment yesterday, nor was Bol. As of early evening, the Bullets had not even been able to reach the tall one.