The notion is growing, although it is not demonstrable, that the key factor in a World Series may not be pitching or managing or home-field advantage or the phases of the moon.Flimsy as the idea may sound, the thread that runs through the last dozen World Series -- and the current one in progress, as well -- is aggressive, indomitable, on-the-field leadership.

Over a full season, seemingly small things may change the course of a dozen games and detemine whether a team finishes first or third: does a team have a pitching staff balanced properly between left- and right-handed hurlers, does it have the depth to survive injuries -- and many other glamorless considerations.

Even in the cladron of the playoffs, there are nuances of strategy since the foes have played each other many times and know one another inside out. The teams have nothing shocking to discover about each other. So, a new pitching "book" on a key hitter, or an injury, or just a lucky break, can shift the balance of a championship series. However, when you play a team that you can see in your dreams, when you face a club that you assume is roughly your equal, there are no new depths of professional apprehension to overcome.

There is, in short, no need to revert back to atavistic, tribal habits like leaning on a few symbolic chieftains.

In the World Series, by contrast, the foe is, by and large, an unknown quantity. Individual players may be familiar, but the other team -- taken as an aggregation of 25 men whose sum may be greater than their parts -- is a mystery. It may be a mistake to attempt overly sophisticated explanations about the performances of athletic teams. At the simplest level, Series teams sniff each other out like bands of animals around a water hole. Only one question is on every mind. After all the speculations and statistics and theories are laid aside, which of us is better?

That is why a very few central players -- count 'em on your fingers, at most -- may play uncharateristically large roles in World Series play.

Certainly, the Philadelphia Phillies think so. That's because the leadership quotient is clearly in their favor and seems to be working to their advantage.

The Kansas City Royals have only one player on their team who has even played a measurable role in a World Series -- team leader Hal McRae. And McRae was merely a part-time spear-carrier on the Cincinnati clubs that lost the Series in '70 and '72. None of the Royal coaches or manager ever left a mark on the big leagues, let alone the Series. When you are looking for a stalking horse -- a man who has done deeds writ large on the October history of your sport -- Hal McRae, despite his 13-for-27 Series batting mark, is not an imposing figure.

Compounding that problem, the Royals' two genuinely great young players -- George Brett and Willie Wilson, both perhaps bound in time for Cooperstown -- are having unaccustomed difficulties. Wilson, the catalytic converter of small uprisings into nerve-shredding catastophes, started the Series zero for eight, with five swinging strikeouts.

"I was feeling the pressure every at-bat," Wilson said after the Phillies had increased their Series lead to 2-0 in Philadelphi Wednesday night. "I was thinking about what I had done before, and how much the team was counting on me, rather than concentrating on just that time at bat. Then I got a walk in the seventh and a (infield) hit in the eighth, so maybe that will get me going."

Brett, of course, has the most famous pain in the butt in the history of baseball. The Royals' most conspicuous hard-nosed player, their bellcow both at bat and on the bases, had to play like an old man with sore feet Wednesday as he waved limply at two important hard smashes past third and jogged the bases like 90 feet was a marathon.

Brett's tortured six innings, his two hits and a walk off Carlton, are surely a profile in baseball courage. Or at least determination. Yet, ironically, his sad style of play was not inspirational to his team because it was in such demoralizing contrast to his normal rampaging kind of leadership. If a one-dimensional slugger -- a Ted Williams, for instance -- played under such conditions, it might be uplifting. wBut with Brett, his appearance at a cautious quarter-speed, no matter how gritty, was an invitation to the Royals to pity themselves and anticipate defeat.

Brett had minor surgery yesterday in Kansas City to lance his hemorrhoids and Royal officials now anticipate that, barring new problems, Brett will start Friday night in game three at 8:15 p.m. (EST) That, nevertheless, might not be the Royals' biggest problem. It may still be a limping, worried, holding-something-back Brett who plays. Only if he slides and gets up in tears might it jack up his teammates. In fact, if history is any criterion they'd probably be more likely to surpass themselves if Brett did not play at all. At least then they would have the psychic freedom of becoming romantic underdogs.

Seldom has a Series team been in more desperate need of saving face than these Royals. They are a tough bunch, known for leading the AL in brawls, collisions and spikes-up slides. That's their true nature and no mistaking it. Anyone who says otherwise is just revealing himself as a once-a-year baseball fan. But, in two Series games, they have done wonders in reversing their reputation. How would a team go about looking more intimidated than the Royals do at the moment? It isn't cowardice, or any such foolishness. The Royals are just a team that has momentarily lost its sense of itself and seems as dazed as a boxer feeling the delayed reaction to a body punch.

The paramount example is when catcher Darrell Porter neglected to slide -- neglected to do anything, really -- as he was thrown out by 20 feet at home, in the first game. The play had a bad scent, just like Eddie Murray's tip-toe to the dish in the second game in '79. The Series is a time to send massages. When strangers from opposite leagues meet, first impressions are important. The whole issue of mutual respect and where the locus of self-confidence lies is still moot.

Porter should have blasted Boone, catcher versus catcher. How hard is his business. Not because it's good baseball, or smart, or would have changed the play, but because it was essential to make the play look good. K.C. Manager Jim Frey stuck with a slumping Porter in the Yankees' playoff series, even against left-handers. But after that game one episode, he was benched.

Also, in game one, Pete Rose one-upped the Royals' best pitcher, Dennis Leonard, with several bits of belligerent gamesmanship after letting himself be hit by a pitch -- charging toward the mound as though angry, firing his bat away furiously like a whirling baton, then standing on first and pointing his finger at Leonard as he yelled. Kid stuff, to be sure, but, also, a trump unless answered in kind.

In the second game, the contrast was just a bleak. Royal starter Larry Gura begged out of the game after only six innings and 82 pitches, despite the fact that he was well rested, looked sharp and frequently throws 130 pitches a game. When you walk up to your manager after the sixth inning and say, "I've lost my fast ball," it only means one thing. You want out. If you want to stay in, if you relish the combat, if you've waited your whole life to get into a nice World Series pitching duel against a great foe, you don't start moaning after 82 pitches. And you leave the manager only one choice: get this guy out of here before he spoils the whole barrel.

Had Gura lasted a few more outs, then perhaps Dan Quisenberry, who retired the first four men he faced, would have wrapped up a save before the Phils ever got wise to his sinker.

By contrast, the Phillies would have needed a gun to get Steve Carlton off the mound. He was exhausted, having pitched on short rest for weeks. He had lousy stuff. He hated the slick, insufficiently rubbed-up balls the umps inflicted on him. And the Royals put 18 men on base against him. But he hung on for 159 pitches -- 59 of them in the last two innings. He was the horse. He didn't stick in for the victory because, after falling behind, 4-2, he surely thought he would lose. He came out for the eighth for one reason -- to rest the emaciated Phil bullpen for one more day.

Carlton went out with nothing, facing a possible humiliation, so the Phils might play better another day. Proof of how little he had was that, once the Phils went ahead, they brought in Ron Reed (not exactly Goose Gossage) to start the ninth. Before the Phils ever rallied for four in the eighth, Carlton was already out of uniform back in the clubhouse, arm in ice, screaming at the TV set, along with the Phillie Phanatic, for the Phils to get more runs.

Carlton's victory was earned. He merited it by coming out for the top of the eighth when he only had one conceivable motive: to help the team.

A team only needs a few thoroughbreds like Carlton. The Phils have three. Carlton, a big winner for the NL-champion St. Louis Cardinals in '67 and '68, sets the mood among starting pitchers. Tug McGraw, a mainstay of the '69 and '73 Mets teams that went to the Series, sets emotional policy in the bullpen, while also revving up the whole bench and stadium in the late innings. And, needles to say, Pete Rose, one of the chambers of the Cincinnati heart on the Big Red Machines of '70, '72, '75 and '76, is the epitome of what a big-game every-day player ought to be.

The Royals have Hal McRae. The Phils have Rose, who taught McRae all he knew, plus Carlton and McGraw. It is not an inconsiderable advantage. Glance back, even swiftly, and the pattern leaps up. The '79 Pirates had Willie Stargell; the Orioles had no one comparable. The '77-'78 Yankees had Thurman Munson, Sparky Lyle, Graig Nettles and a cast of gamers; the Dodgers ended those Series whining lamely. The '75-'76 Reds had Rose, Joe Morgan and Tony Perez, the standard by which glamour Series leadership is measured. The '72-'73-'74 Oakland A's had Sal Bando, Joe Rudi, Reggie Jackson, and Catfish Hunter.

What we see here is not just a quality of talent but a certain distinct flavor of personality -- dogged, inspirational, rise-to-the-occasion players who seem surrounded by an aura of certitude of eventual victory.

By comparison with these crews, the Royals suddenly seem a bit mild-mannered, like friendly young school teachers. That could change. If George Brett takes somebody into left field on the double-play pivot. If Hal McRae has a third baseman for lunch. If Willie Wilson suddenly starts making fools of Phillies the way he has terrorized fielders throughout the AL.

"Everybody likes to deny it," said Dallas Green after game two, "but baseball is still a game of emotion. Especially this time of year. And, right now, we've got it all."

The Royal hopes do not lie in medical reports or pitching matchups. They lie in their own hearts. The only way they will take the World Series from the Phillies is if they take if from them by force.

And, at this juncture, that will be far from easy.