If the Pittsburg Pirates don't understand now, they never will.

Everything that the Baltimore Orioles epitomize, every idea about how true team baseball should be played, every tactical trap and gambit in Manager Earl Weaver's repertoire, was displayed in Three Rivers Stadium today.

If the Bucs don't grasp why the Birds are on the verge of routing them in the World Series -- leading now three games to one -- then they weren't watching the gloriously intricatre, yet bludgeoningly simple 9-6 O's triumph this slate-gray afternoon.

The sky might have been a blackboard today on which Prof. Weaver could draw his diagrams and illustrate his lecture. No series game was ever more a treat for the mind as well as the emotions.

Perhaps the Orioles are not the best team of their age -- the most talented or the most unbeatable. But in this chilly crucible of pressure today, they showed why they are a fan's dream come true -- a genuine ensemble of blended skills.

This was the day when Baltimore's "deep depth" fell on the Pirates like an anvil dropped from the upper deck.

The Bucs knocked out starter Dennis Martinez with four runs before he got four outs. So Baltimore wheeled in Sammy Stewart, Steve Stone and Tim Stoddard -- the first two holding the fort, the last getting the win.

When the Birds rallied from a 6-3 pit in the eighth, scoring six runs while the Bucs' relief master Kent Tekulve was on the mound, Weaver unleashed an arsenal of pinch hitters.

Who were these brutes who crushed the powerful Bucs, who were these giant pinch hitters who hit a pair of bases-loaded doubles into the right field corner in the same inning?

John (Brother Lo) Lowenstein and Terry (Crow) Crowley, that's who. "My journeymen," said Weaver proudly.

Some will say that the Birds, trailing by 4-0 and later by 6-3, won this Series masterpiece on luck.

"God's looking out for them," said Pirate second baseman Phil Garner, who must be wearing blinders.

The Orioles didn't steal this one. Not unless it is theft to set steel traps in the woods, then go to collect the pelts of the bears that walk into them.

That six-run eighth, which has probably shattered Pittsburgh hopes of a world title (only five teams in history have come back from the dungeon of 3-1) was the strategic crescendo of this Series.

That inning did not unfold with the sudden brilliant revelation of a triple-jump in checkers, but with the probing, deeply-layered and viciously inexorable feeling of a multi-move chess checkmate.

"Most of managing is foolishness; people don't understand it," said Weaver before the game. "Only one thing matters. When the game is on the line, do you have the right men to send the plate against the pitcher they are going to have out there?

"Have you held your fire so that you still have the right man for the right spot?" If you do, then you're managing your club."

What Weaver did today went beyond managing to some large word. He conceptualized an entire game -- held it in his hand from front to back, then squeezed until the Pirates passed out, never knowing where the presure came from.

"This is the first time in this Series that we've been able to keep the gun loaded right to the very end," said the beaming Weaver afterward. "That's why all those left-handed hitters were sitting there next to me all day. We were waiting for the big spot."

Never doubt that the Pirates helped the Orioles achieve their moment of illumination when an entire watching nation could find out the hidden source of all those Oriole victories.

Pirate Manager Chuck Tanner will always wonder why, with that 6-3 lead, he did not bring in Tekulve to start the eighth.Instead, he left Don Robinson, the 22-year-old righty, in the game to start the inning -- and load the bases with one out.

By the time Tekulve arrived, after singles by Kiko Garcia and Ken Singleton, plus a walk to Doug DeCinces, that bear trap had already been set. Only Pittsburgh didn't know it.

Up came Lowenstein, the 11-year vet Weaver calls "my man Lowenstein."

Of course, Lowenstein could have grounded into a double play. Baseball is no exact science. But to any of the 50,383 who were here today, it would not have seemed appropriate.

After all, the Pirates, who had 17 hits in this fourth game, had squandered opportunities for hours. Throughout this 3 hour 48 minute marathon, the longest nine-inning game in World Series history, they were a team in search of their own comeuppance.

Hadn't Ed Ott. waved home foolishly by Coach Joe Lonnett, been out at the plate by 20 feet on a throw from Al Bumbry? Hadn't Bill Madlock grounded into a bases-loaded double play? Hadn't the same Madlock opened a three-run Oriole third inning with a throwing error that paved the way for back-to-back doubles off the left field wall by the red-hot Garcia and Singleton?

And above all, but lost in the clutter, hadn't right fielder Parker -- he of the $900,000 salary -- made an atrocious play to start the eighth when he broke late and let Garcia's simple fly ball fall in for a hit?

Every thread in the Orioles year-long drama seemed woven together in that moment. When Lowenstein lashed a liner over Stargell's leap at first and into the corner for a two-run double, it seemed a natural development in plot.

Suddenly, trailing, 6-5, it was Weaver in the driver's seat. "Tanner had burned up his one good lefty reliever -- Grant Jackson -- to escape an earlier jam. Tekulve was his man -- his only man.

Weaver, however, had other ideas. He picked switch-hitter Billy Smith to pinch hit, knowing that he would be walked intentionally. "Somebody had to be sacrificed." Weaver said. "I wanted the big spot to be for Crow."

Few know Crowley or realize that he has been a valuable sub on two previous world champs, "Terry's got one of the highest pinch hitting averages in history," said Weaver, citing a stat that he has learned recently.

If Lowenstein's double barely eluded the leap of Stargell, the Buc who had a single, double and homer today, then Crowley's had two-bagger written on it from the start.

As the tying and go-ahead runs sped across the plate, one look at the Oriole scorecard showed an incredible sense of order and cleanliness -- a proof, if you will, of the systematic mind behind the execution.

Far from being disrupted by those three straight lefty pinch hitter -- just the fellows the O's so desperately needed to face the submarineg Tekulve, the Birds' defensive lineup for the next inning had been improved.

Gary Roenicke, Rich Dauer and Dave Skaggs were now out of the game, but, Rick Dempsey, Smith, and Lowenstein were ready to replace them.

With Mark Belanger joining them afield in the bottom of the eighth, Baltimore had managed to rip apart its entire lineup in a do-or-die crisis while actually improving its defense for the moment when that was needed.

Predictably, the Birds used every nonpitcher on their roster except Bennie Ayala -- and he struck the crucial home run the day before. Deep depth, indeed -- fathomless.

After Crowley's game-winning hit, goofiness brole loose. Perhaps the O's knew they couldn't lose. Despite the fact that they had used four pitchers, their two best late-inning relievers -- Don Stanhouse and Tippy Martinez -- were still fresh and unused.

So flushed was Weaver, so confident of his bullpen, that he let Stoddard hit for himself, instead of beckoning yayala.

"I was shocked, I couldn't believe it," said Stoddard, who finished with three shoutout innings, including a game-ending strikeout of Ott.

"I've never batted in the majors. In fact, I've never gotten a hit in organized baseball. In the American Association (the minors) I struck out every time I ever batted.

"Earl said, "Take everything until you have two strikes on you," said the grinning 6-foot-7, 250-pound Stoddard.

"So, I swung at the first pitch," said Stoddard.

And bounced an RBI single to left over Madlock's leap. And got to make a glorious wallowing slide into second base when Bumbry followed with a chopper that went for an RBI forceout.

The filthy Stoddard trotted back to the dugout with a beaming smile under his walrus mustache.By the time he returned to the mound, however, he seemed as serious as his 95 mph fast ball.

"Earl probably didn't know if he was doing the right thing in letting Stoddard bat," Lowenstein said, "But that's just Earl. He'll gamble.

"He's a master tactician. He pulls us all out of the hat at exactly the right time. We're not a team of stars, but we all get our opportunity to twinkle a little."

What is the secret of Weaver's magic potion? Now, he has his ace, Mike Flanagan (23-9) ready to start Sunday (4:30 p.m.) against Jim Rooker (4-7). f

How can Weaver call on nine pinch hitters in this Series and have eight reach base? How, with Tekulve -- the praying mantis -- on the mound, can he have just the proper men left?

"If Earl knew the magic formula, Lowenstein said. "I'm sure he'd bottle it.

"But I don't think he'd sell it to the public, even if it could make him rich. Knowing Earl, I think he'd just keep it all for himself".