The Baltimore Orioles probably knew the truth as they flew home from miserable, misty Toronto late Sunday night. But this evening, back in the unfriendly confines of Memorial Stadium, they were finally willing to talk about it.

The End, that is.

"What about the race?" the Birds' Steve Stone was asked after being thumped, 8-3, by the Detroit Tigers.

"Well," said Stone, "I think Ronald Reagan has a real good shot."

"No, no, Steve, the pennant race," Stone was prodded.

"Well, it appears the Yankees have a six-game lead," said Stone. "That about sums it up."

Of course, the defending American League champions haven't officially conceded, even though New York's 5-4 win tonight over Toronto gives it that half-dozen game advantage with only 18 to play.

"We'll keep playing hard," said Ken Singleton. "We'll play it tough down to the last day.

"But what I'll remember is how it took us so long to get rolling early in the season. Sometimes you can put much burden on yourself that you cannot overcome it."

Memorial Stadium was as quiet and casually half-concerned tonight as it was in those early April and May days when baseball seemed sleepy, pennant races were far away and the Orioles were busy digging their hole.

Only a month ago, when the Orioles and Yankees played five games here before the biggest house for any series in major league history, this ball yard was a huge bubble of pressure, being inflated beyond specifications each day.

But now, that bubble has burst. The pin that did the trick was the sharp tack called arithmetic. The Orioles lost this night in a mere silence begat by Yankee numbers: 17 New York wins in 19 games.

Even when the Orioles took a two run lead off Tiger winner Jack Morris, the middling crowd of 10,992 seemed disinterested. The message that Toronto took a 1-0 lead over New York in the top of the first inning did not stir them, either. Why should it? They have been observing the same scenario every night for four weeks since they left this town. The Yanks scored three runs in their first at bat to show who was boss. And the O's began to slide.

The gentle, resigned, yet castigating boos began the instant that Steve Kemp hit a game-tying two-run homer off Stone in the sixth inning, dead over the center field fence.

The Orioles' angst increased exponentially in the seventh as the Tigers scored four more runs. When the tie breaker crossed the plate on a Lou Whittaker double, the little gathering released the last of its frustrations with jeers.

But when Stone finally knocked himself out with an intentional, bases-filling walk, followed by a very unintentional run-scoring walk, the stadium folk were too worn out with this tedious script to make any noise.

The only volume in the joint came from a gang of Yankee fans behind the vistiors' dugout, who gave a roar for Stone's exit, presumably pleased to have another piece of evidence for their case that Goose Gossage, not Stone (now 23-7) deserves the Cy Young award.

Stone isn't sure that the Tigers beat him tonight. His vote would go to umpire Russ Goetz. "I had a wonderful curve ball but there was no strike zone for it," said Stone. "I told the umpire, "There has to be a strike zone somewhere. High? Low? Just tell me where it is and I'll throw it there.'

"He just wouldn't call any curve a strike. When the plate is two inches by two inches for my best pitch, then I might as well phone in the game," said Stone, who threw 79 curves out of 114 pitches.

The Orioles, however, are honest enough to know that it isn't Goetz who has brought them to their current state of affairs.

"It's the Yankees who are makin' things look so bad by playin' so good," said Earl Weaver, who has a huge head cold exactly like the kind that had him talking like a foghorn during the last three games of the '79 World Series as his Birds went down the tubes. "Anyway you cut it, we've played well. They've just played better," said Weaver.

Since June 15, the O's are 56-28. Since they last met the Yanks, they are 18-10. Even during New York's 17-2 streak, the Birds have played .600.

A month ago, Weaver said that .650 ball would be good enough for his Birds in their scoreboard-watching war. His math was wrong.

No one quite relishes being a sarcastic, you'll-never-get-me-to-say-uncle loser like Weaver.

"Aw, the Yankees could mess it up," he said, downright cheerful as always when Oriole affairs are bleakest. "We might have a thrill yet. We gotta put some pressure on 'em, let 'em know we're still in it. Oops, I don't use the word pressure, do I? Well, we gotta win some games in a row.

"It's going to be tough. The Yankees are gonna have to have a funny streak, and they ain't been too funny lately."

These are the final days when second-place teams think back on their sins while hoping for drastic and "funny" miracles. The Orioles will have many painful memories -- losses to expansion teams in Seattle and Toronto prominent among them.

But most of all, Baltimore must recall how mundanely it has played in Baltimore. The Birds have actually played better on the road this season than at home.

Just four weeks ago, 253,363 fans marched out of Memorial Stadium convinced that they had seen the climax of one of baseball's noblest storybook comebacks. Tonight, a mere 10,992 took the trouble to read the beginning of the final chapter of that long, long book the ending of which they never would have guessed just one fleeting month ago.