When you have a good thing going, why switch? For the third straight year, the Baltimore Orioles made a right-handed college pitcher their first choice in baseball's amateur draft yesterday, selecting Stanford junior Mike Mussina.

Mussina was the 20th player drafted. No. 1 was Chipper Jones, a high school shortstop from Jacksonville, Fla., who was taken by the Atlanta Braves. Only 10 collegians were chosen in the first round, fewest since 1980.

In 1988, the Orioles' first choice was Gregg Olson of Auburn, who went on to become the 1989 rookie of the year in the American League. The 1989 selection, first overall, was Ben McDonald of Louisiana State, presently battling a blister as a pitcher at Class AAA Rochester.

It took the Orioles two months of hard bargaining to get McDonald's name on a contract, but Mussina indicated yesterday that he did not foresee a repeat of that marathon negotiation.

"I don't want it to run to August," Mussina said by phone from Omaha, where Stanford is participating in the College World Series. "I haven't talked to the Orioles and you can't predict what will happen the next couple of weeks, but I think things will work out. Right now I expect to pass up my senior year and get on with baseball.

"I'd like to start as high as possible, but Hagerstown or Frederick, it doesn't matter. My main feeling is more or less relief that the draft is over."

The Orioles tried once before to sign Mussina and failed. That was in 1987, when they drafted him in the 11th round out of Montoursville (Pa.) High School. Mussina was projected as a first-rounder that year, but his father sent all major league clubs a letter saying that unless they were prepared to offer a $350,000 bonus, the youngster would attend Stanford.

The personal intervention of the late Edward Bennett Williams, then the club owner, was not enough to alter the family's target. Presumably, the price tag hasn't changed, but a 94 mph fastball and a tricky knuckle-curve figure to be worth the price, despite some inconsistency and the memories of an elbow problem that forced him to watch the second half of the 1989 season.

"I'm excited and pleased to get another shot" with the Orioles, said Mussina, a friend of another Stanford product, Orioles left-hander Jeff Ballard. "I like the idea of coming back to the East Coast."

Mussina, 6 feet 2 and 190 pounds, started against Georgia Sunday night in the College World Series and carried a 2-0 lead into the sixth inning. By the time he left, it was 4-2 -- and before the side was out, Georgia had 11 runs. Mussina's record this year is 14-4 with an earned run average of 3.35.

"I was doing well for five innings or so, then all of a sudden I was throwing batting practice," Mussina said. "That happens sometimes."

"He has a good arm, the makings of three-plus pitches and we see him as a starter some day for the Baltimore Orioles," said John Barr, the Orioles' scouting director. "He was a lot higher up than 20th on our list and we were able to get someone we thought would be selected before we picked."

Mussina was rated 26th by Baseball America. That publication's top man, and the one generally recognized as the best prospect in the draft, was high school right-hander Todd Van Poppel of Arlington, Tex., chosen 14th by the world champion Oakland A's.

Van Poppel was wooed by the Braves, but he informed them that he planned to attend the University of Texas and had hopes of pitching in the 1992 Olympic Games.

The A's could take a chance on changing Van Poppel's mind, because they had seven of the first 66 selections in the draft, five as compensation for the loss of free agents Dave Parker, Tony Phillips and Storm Davis. They will lose their rights to Van Poppel if he enrolls in college.

Red Murff, the Atlanta scout who signed Nolan Ryan for the New York Mets in 1965, told the Associated Press that Van Poppel had the best stuff he had seen since Ryan.

But the Braves need help too badly to run the risk of failing to sign him. In Jones, they got a switch-hitter who batted .488.

Although more than 1,000 players are expected to be drafted before the process ends Wednesday, names of only the first-rounders were disclosed yesterday. The rest will be revealed in about a week.

The second and third selections also were high school players. Detroit took 6-7 outfielder Tony Clark of El Cajon, Calif., a .543 batter who has signed a letter of intent to play basketball at Arizona. Philadelphia chose catcher Mike Lieberthal, a .500 hitter from Westlake Village, Calif.

The first collegian and first pitcher selected was right-hander Alex Fernandez of Miami-Dade Community College, picked fourth by the Chicago White Sox.

The New York Yankees, exercising a first-round pick for only the second time in 12 years, chose outfielder Carl Everett, who batted .519 for Hillsborough High in Tampa. Hillsborough produced major-leaguers Dwight Gooden, Gary Sheffield and Floyd Youmans.

The Montreal Expos, with 10 selections in the first 53, picked Shane Andrews, a high school shortstop from New Mexico who batted .546. List of first-round picks, Page E6