The time is quickly arriving when the Baltimore Orioles will have the rest of the American League East in a kind of statistical vise.

After recording their 20th victory in 25 games tonight with a 5-2 win over the obliging Boston Red Sox, the Orioles' division lead reached a formidable five games over Milwaukee and 5 1/2 games over both Detroit and New York.

The Baltimore blitz has been so sudden, as the Orioles have won 13 of their last 15 games by a staggering margin of 104-36, that the shape of the AL East race has been bent into an almost unrecognizable shape. What looked like a five-way pennant race as recently as two weeks ago is now strictly an issue that the Orioles can settle with their own hands.

If, for instance, the Orioles play .500 ball in their last 26 games for a 95-win season, then one of Baltimore's pursuers would have to play better than .700 ball just to gain a tie. Put another vivid way, if the Orioles finish just 13-13, then the Brewers would have to play 18-6 to beat them while Detroit would have to go 18-5 and the Yankees 19-6 to win the title with 96 victories. Toronto, so recently in the thick of the race, would have to go 19-1.

As an added Baltimore advantage, the Brewers, Tigers and Yankees all play a slew of games with each other, all trying to pull one another down the ladder as they climb toward the Orioles. As another example of Orioles luck, they still have four games next week in Fenway Park against the losing Red Sox. If Baltimore survives four tough games this weekend in Yankee Stadium (while Milwaukee and Detroit batter each other), then the Orioles' position one week from now could be almost prohibitively secure.

All this has a certain element of turn-about-is-fair-play. In both 1980 and 1982, Baltimore spent the whole summer chasing, first the Yankees, then the Brewers. In both seasons, the Orioles finished with the second-best record in all of baseball. And in neither year did they even make the playoffs. Now, they have all the inherent physical and psychological advantages of being on top.

Not so long ago, on Aug. 12, the Orioles had lost seven games in a row and were in fourth place. Now, after 3 1/2 weeks of snazzy .800 ball, healthy and hot Baltimore has its fate not only in its hands, but within its reasonable control.

"If, for some reason, we don't win the pennant, we will have only ourselves to blame," said Mike Flanagan, who increased his record to 10-3 tonight with his third straight gritty, gimpy, improvisational victory.

The Orioles got RBI hits from five different players--Joe Nolan (double), Glenn Gulliver (GWRBI), Lenn Sakata, Ken Singleton and John Lowenstein (solo homer in the eighth). Red Sox starter Dennis (Oil Can) Boyd was roughed up repeatedly in his five innings by the Orioles, who've hit .317 for 13 games.

After Flanagan allowed 10 hits on 100 pitches in 6 1/3 innings, Tippy Martinez provided one of the more splashy saves of this season.

Few things are rarer in baseball than an exceptional left-handed relief pitcher. You can count 'em on one hand. Let's see, there's Martinez and . . .

Hmmmm . . .

At any rate, there is definitely Tippy Martinez. It would probably be stretching to put anyone else, except Steve Howe of the Dodgers, on his level.

The southpaw with the 8-3 record, 2.70 ERA and 15 saves entered the game in the seventh inning with the Orioles clinging to a 4-2 lead and runners at second and third bases with only one out.

Martinez's mission impossible was simple, should he chose to accept it: get out Wade Boggs, the league's leading hitter (.366) and Jim Rice, the league's top home run man.

With the crowd of 27,037 exhorting on every pitch, Martinez gave one of his premiere performances of a sterling season. Boggs fanned on three pitches, finishing with a homely half-lunge at a breaking ball in the dirt.

Rice did little better. On a 1-2 pitch, Martinez unleashed the hard hook, the terrible downer, the golden hammer, your Uncle Charlie. Call it by any name but when Martinez throws his best curve to the precise low outside corner, not even Rice hits it. Strike three waving.

For a few final style points, Martinez walked two men in the ninth to bring Boggs to the plate again as the tying run. Early this year, Martinez walked Boggs to force home the winning run in a game in Fenway; restitution was on his mind. Boggs slapped a grounder back to Martinez, who started a game-ending double play. Thus ended the 57th game of 1983 in which the Orioles' pitching staff had allowed two or less runs. The team ERA for the last 26 games is 2.35.

Flanagan work was all grit, Martinez' mostly gift.

"Everything hurts," said Flanagan to GM Hank Peters. "But not as much when you win."

Flanagan's three-game winning streak is fairly remarkable since the body of evidence would seem to indicate that Flanagan, wearing a bulky knee brace and bereft of his normal fast ball, has nothing on the ball but his heart. At one point this evening, Flanagan reached an amazing juncture when he had not struck out a single man out of the previous 107 batters he had faced over five starts.

In his last two starts, over 14 2/3 innings, only four batters have swung and missed at a Flanagan pitch; his work has been batting practice with brains.

"I don't like to pitch this way, but you give what you've got," he said. "I believe I can still get them out with finesse."

As for Martinez, he is finally being given bullpen star prerogatives. "Joe (Altobelli) is treating him like the Goose (Gossage)," said Flanagan.

According to Martinez, he was asked to warm up more than 300 times last year, but was used only 76 times. That's more than 220 extra "ups." This year, Martinez says he's only gotten up "a handful of times, probably less than 10" when he didn't come in the game. He's never wasted more than one "up" in any game this year. Last year, he once warmed up seven times in one game and was never used.

"It makes a big difference," said Martinez. "Tonight, I was so rested that it seemed like I hadn't thrown in years."

Or been hit hard in almost that long.