Periodically a baseball team of few conspicuous talents develops an internal harmony and a knack for good fortune. Few can anticipate the coming of this manna from heaven and none can predict the sad day of its departure.

But make no mistake, the Baltimore Orioles have played this month as though they have angels on their shoulders. Today before a crowd of 34,299 that brought the three-day total for this series to more than 111,000, the Birds hammered New York, 6-0, for their ninth victory in 10 games this month and moved into a first-place tie in the American League East with the Yanks and Boston, pending the outcome of the Red Sox' second game today.

The Orioles, playing with four rookies and a slow ball pitcher, put together an almost model game.

Ross Grimsley, using a change-up and an even slower palm ball that the Yankees accused of being a grease ball, pitched a five-hitter for his first shutout since 1975. When Grimsley was not coaxing New York's free swingers into 16 outs via the ground ball, his three outfielders were making brilliant running catches to cut off extra-base hits.

At the plate the O's knocked out Yankee ace Ed Figueroa, got six extra-base hits, gambled on the base paths for three extra bases (showing up the arms of all three Yank outfielders in the process), hit to the opposite field in the clutch and advanced runners selflessly.

Every rookie lent a hand. Just when Figueroa seemed to have gotten in a groove, striking out three O's in a row, Eddie Murray smoked a home run into the first row of the rightfield bleachers in the second to shake the Yankee confidence.

"That ball was a pea," said the O's Tony Muser. "It was in the seats in half a second. Fastest homer of the year. We're a team that needs momentum. With us, one thing leads to another and that got us going."

Murray added a sacrifice fly in the eighth after Ken Singleton, hitting .341, had sacrificed his average to advance Pat Kelly from second to third with a grounder to second.

While Murray, the rookie with 13 homers whom Manager Earl Weaver said "every team in baseball wanted to talk trade for during the offseason," was having a typical day, slumping Billy Smith salvaged some dignity.

"Easy Billy," who has seen his average slide from the best in baseball in May (over .450) to .235, reached a l-for-17 nadir after fanning in the first. In the third his ill luch continued as what would have been a three-run homer to right blew foul by a foot.

"I've been hitting the ball hard, but in awful tough lack. How do you swing hit 'chinkers' and 'flares?" They won't let you throw the ball out there into the open spaces."

But Smith persevered, tripling on the next pitch as his hooking drive eluded the atrocious stumble-and-jump of right fielder Lou Piniella on the warning track. Two runs scored for a 3-0 lead.

Not to be outdone, young Kiko Garcia doubled to the opposite field to drive in the fourth run and Dave Skaggs started a rally with a walk and scored. The veterans followed the kid's example as Kelly. Singleton and Doug DeCincth all stretched line singles toward the alleys into doubles by challenging the Yankee arms Cincinnati exposed in the last World Series.

"We have to get excited every day, almost like a football team," said Muser, "he Yankees never get excited. They can wait for a Munson or Nettles or Chambliss or Jackson to drive in five runs in a game. We have to have nine guys to one-for-four."

Today seven players shared the eight hits, with six different men batting for the extra bases. The Birds' margin of victory for the entire season before today was just six runs, 349-343.

"It just shows how we can't afford to lose many of the close onces," said one Oriole.

The Baltimoreans even managed to win the inevitable postgame sparring that goes on between Weaver- and Billy Martin-managed teams. Martin, who almost never loses a game without having at least one barbed excuse, maintained. "It's obvious to everyone that Grimsley is now throwing a grease bail. That's why he's winning again. But the umpires refuse to call it."

Weaver, told of the charge, put his hand over his lips and said with mock shock. "Oh, my goodness." Then added, "Where would he learn a thing like that?" After a moment's pause Weaver said conspiratorially, "Don't tell Billy this, but (pitching coach) George Bamberger used to throw a greaser in the Pacific Coast League . . . I think."

Grimsley denied all ("just my usual junk"), while Bamberger explained that the new pitch was a palm ball. "It gives Ross a change-up even slower than his regular one, if that's possible. Now he has a change-up off the change-up. If the hitters want to think it's a grease ball, let 'em. Just gives 'em one more than to get mad about.

"Anyway," Bamberger said mysteriously, "we don't cheat around here. . . any more."