The Baltimore Orioles may have won a World Series rainout last night.

"After it's all over, if we lose, I might come up with an excuse and blame it on this rain," Oriole Manager Earl Weaver said after a steady downpour postponed the first game of baseball's 76th World Series between his club and the Pittsburgh Pirates until Wednesday at 8:30 p.m.

(It was the first time in history that the first game of the Series was washed out.)

"But right now we're all happy because this means we'll get to go with a four-man rotation instead of just three." said Weaver. "Now, Dennis Martinez is guaranteed a start.

"After working his rear off all year, leading the league in complete games, it was really tough to tell him that he probably wouldn't get a turn in the Series. He's a great kid and he was really down in the dumps.

"He didn't say anything, but you could see it in his eyes. Now, I can sleep good a couple more nights because I don't have to be the one to choose over him," Weaver concluded.

Something else could be seen in the eyes tonight -- the eyes of the Orioles. They and the Pirates are scheduled to play five consecutive games before their first "travel day" next Monday (if the Series goes that far).

Game 2 will be played Thursday night then the action shifts to Pittsburgh on Friday, as orginally scheduled.

All games will be on ABC-TV (WJLA-7 in Washington).

If the Birds had their way, they'd play this Series in back-to-back doubleheaders. The deeper the O's and their opponents are forced to reach into their pitching bag, the better off the Birds think they are. It's axiomatic.

Not, since the Pirates have preferred using a five-man rotation all season, it is possible the Orioles may see five different Pirate pitchers.

At any rate, a fourth-game match between Martinez and Pittsburgh's Jim Biddy is a near certainty and the O's like the sound of that.

Though he, of course, did not reiterate it last night, Weaver has insisted all season that "the deeper we go into the pitching staff against someone head to head, the greater our advantage. No one in baseball has so many good pitchers as we do."

The quality of the Orioles' Nos. 3, 4 and 5 starters is their greatest pride, and now, to a greater degree than before, it may show.

"We might even get a start for Steve Stone," said Weaver. "That would be a luxury. We wouldn't do it probably if our backs were up against the wall, but . . ."

In other words, if the American Leaguers led 3 games to 1, they could start Stone in the fifth game and still have first- and second-game hurlers Mike Flanagan and Jim Palmer on tap for the final showndowns back in Baltimore.

If it were Baltimore that faced tough times, then Flanagan and Palmer would come back to pitch the fifth and sixth games.

About all this, the Pirates couldn't care less. The Orioles, especially Weaver and scout Jim Russo perched in his office tonight, think baseball is chess. To the Bucs, the game ain't that tough. It's just country hardball, about as complex as checkers.

"We have six starters who are of roughly equal ability," said Manager Chuck Tanner of the National League champioins, "so this doesn't mean anything to us. We're just glad not to have to play on a bad field."

Since the Pirates have six pitchers with at least 10 wins, but none with more than 14, it is a matter of indifference how many of them are used or in what order. Tanner only wants five or six decent innings out of them anyway before he brings on his waves of relief pitchers.

Often in the previous 25 Series games that have been rained out, there have been juicy debates, chances to second-guess Commissioner Bowie Kuhn for his decision.

This time, it was simple and boring. It rained, so they didn't play.

"The first weather report I got was when I arrived at the park at 6:30 p.m.," Kuhn said."It was a bad report -- rain falling on my head.

"We'll just play straight on through and have the same times as scheduled."

The only moot point was whether Thursday's Game 2 should be played in the afternoon (for easier travel) or at night (for a much larger television audience). Since travel from here to Pittsburgh doesn't amount to much, it will be hard for the predictable Kuhn taunters to say his decision was dictated by TV.

"The only conversation I had with ABC was when they called at 8:15 (15 minutes before game time) and asked how it looked. I said, 'not good'," related Kuhn.

"The only one person who memtioned perhaps waining longer was Edward Bennett Williams' daughter," Kuhn said jovially. "She was seeing her first World Series and told me she'd like to see it played."

The originally scheduled pitchers -- Flanagan and the Buc's Bruce Kison -- will start the recheduled Game 1.

Flanagan threw for a few minutes in the bullpen in the rain tonight after the postponement was announced. Afterward, on his way to the shower, he said out of the side of his mouth, "Another laugher."

Flanagan, the majors' leading winner, may be the only casualty of the rainout. Should the competition go seven games, he probably would not get to pitch three times.

The 23-win southpaw is the man on Pirate minds at present. On the Pittsburgh bulletin board before the game was a sign, "No Hitting" -- meaning no batting practice because of rain. Next to those words was an arrow and another message: "Flannigan (sic) said it would not help us!"

The O's were equally aware of Kison for another reason. In the '71 Series he set a record by hitting three Bird batters. Rookie wildness or not, that made him a reputation that has persisted.

"I pitched against him in the minors," said Ray Miller, the Oriole pitching coach, "and there were plenty of fights when he worked. He'd brag that hitting two or three guys a game was just part of the way he pitched.'"

That explains why every available Baltimore lefty hitter has been pressed into service to avoid Kison's sidearm intimidation. "It annoys you more," Miller said, "because Kison is a control pitcher."

At present, Baltimore is content. Flanagan will work for the second straight time with an ample five day's rest. Kison, however, has gone 10 days between starts and notes, "sometimes too much rest is as bad as not enough."

Another day of moisture would throw the Birds into the same boat of having a staff with more rest than it wanted.

"Our (weather) reports," said Kuhn, "leads us to believe that it will be all right."

At that, Weaver sagely nodded. "The weather report for Baltimore is always the same, 365 days a year -- rain," the little tomato farmer said. "But sometimes it doesn't."