SEATTLE, AUG. 14 -- Ben McDonald is a veritable good news factory. It is a trait of which his parents long have been aware, leaving them so fearful of missing the next eye-opening development that they gathered by a telephone late Monday night and early this morning at the workplace of McDonald's mother in Denham Springs, La., to get inning-by-inning updates from the Kingdome.

The Baltimore Orioles too are learning of McDonald's proclivity for producing positive -- and positively breathtaking -- results. The phone lines carried only joyful accounts to Denham Springs, as McDonald limited the Seattle Mariners to four hits and two runs over 8 2/3 innings to lead the Orioles to a 3-2 victory.

The strapping, 22-year-old rookie right-hander won for the fifth time in five major league starts and captured his sixth big league decision without a loss, breaking Jerry Walker's club record (1957-59) for consecutive victories at the start of a career. His fastball had its usual pop, but what separated this from his last three starts was a baffling curveball and change-up that he threw for strikes consistently and used to befuddle the Mariners.

"I think maybe it was the best stuff I've had this year, especially on the curveball," McDonald said of his top performance since he shut out the Chicago White Sox on four hits with 85 pitches in his initial major league start 3 1/2 weeks ago. "If I throw the curveball over the plate like that, I'm going to be successful."

McDonald (5-0) escaped a two-on, two-out jam during a comparatively shaky first inning, and he retired Ken Griffey Jr. with two outs and a runner at second base in the third. He was touched only for Edgar Martinez's fifth-inning double, which led to Seattle's first run, and three singles -- two by Alvin Davis and one by Omar Vizquel.

He retired 10 of 11 batters between the first and the fifth and 12 of 14 before giving way to Gregg Olson in the ninth. McDonald finished with three strikeouts and three walks, and his ERA rose to 1.56 over 11 appearances this year.

He has allowed only 26 hits and seven earned runs in 36 2/3 innings as a starter. Opponents are hitting .201.

He is doing it with a limited repertoire that includes two kinds of fastballs, plus a curveball and change-up that have been erratic. He plans to work on a forkball for next season.

As the Orioles scratch to remain in contention in the American League East -- at 56-58 and six games behind Boston entering tonight's game here -- they are relying on a fuzzy-cheeked staff from which 41 of their victories have been won or saved by a pitcher 23 or younger.

McDonald quickly has become the rotation's anchor.

"I was confident about myself {before being moved into the rotation}, but I didn't expect to do this," he conceded.

Naturally, he continued to draw raves.

"He's a gifted, special kid," said Seattle Manager Jim Lefebvre, whose team fell to 58-58, lost for the sixth time in seven games and has scored only 32 runs in 12 games this month. "Forget 'gonna be.' He's a helluva pitcher already."

Orioles Manager Frank Robinson said: "He had good control and command of his pitches. . . . It's not that he's getting better, it's that he's starting to feel more comfortable out there and starting to settle in and do some of the things he's capable of doing.

"When he has his good stuff, he doesn't care who's out there. It was not what Seattle didn't do, it's what Ben McDonald did. . . . He's earned my respect."

Olson struggled for the second outing in a row. Plagued by wildness again, he allowed Martinez's RBI single but got the final out -- and his 27th save -- on Scott Bradley's liner to second baseman Rene Gonzales to strand runners on first and third.

Brian Holman was solid in extending the Seattle starters' remarkable streak of pitching at least into the seventh inning in 31 of the last 33 games. He ended with a complete-game six-hitter.

But Holman (11-8) took the mound on the wrong night, for McDonald made Cal Ripken's RBI double in the first and a two-run fourth inning stand up. Holman's only glaring mistake was a balk that allowed Chris Hoiles to take second with two out in the fourth; on the next pitch Craig Worthington singled to center to give the Orioles a 3-0 lead.

And all the while, Larry and Rebecca McDonald stood by at their toll-free number at the Vulcan Foundry in Denham Springs; Orioles public relations director Rick Vaughn was their connection in the press box here.

"I talked to them earlier {Monday}, and they told me" about the arrangements, McDonald said. "I told them they were crazy. . . . They've been with me in this since I was knee high. They saw every game up through college, went to the {1988} Olympics in Korea, follow every game now. It makes all the difference in the world to me."