Boston Red Sox slugger Jim Rice was abruptly introduced last week to one of the oldest, yet most currently fashionable strategies in baseball - the drastic defensive shift.

"Don't those guys have 10 men on the field?" asked Rice, staring at four Kansas City Royals cluttering the Fenway Park outfield on Monday night.

"Nope," answered the home-plate ump."They just moved an infielder to the outfield."

"Is that legal?" asked the incredulous strong man.

Rice, and many another perplexed hitter, is finding that almost anything is legal when it comes to defensive development these days.

"If we had enough men, I'd put one up in the left field (Fenway) screen when Rice is at bat," said Kansas City Manager Whitey Herzog, whose Rice Shift is probably the first defense ever to employ four deep outfielders.

"Say, is there a rule that we have to have a catcher?" continued Herzog. "With nobody on base and less than two strikes on Rice, we could put the catcher in the outfield, too, and just let the pitches that Rice didn't swing at bounce off the umpire."

Baseball rules say a catcher is mandatory and that the other eight men have to line up in fair territory.

Since the days when Connie Mack stationed his players with a subtle motion of his scorecard, every conscientious team has "studied the hitters" and considered defensive positioning an art.

But in recent years, it has also become a science, and a surprisingly unpredictable one.

"The Rice Shift is an eye-catching version of what many teams are doing," said Ray Miller, Baltimore pitching coach. "We chart what every pitch is, where it is and where it is hit.

"In the old days, people thought only a few hitters had major tendencies. Now it seems like almost every hitter does. And not just little ones, like, 'Play him a step to right."

Drastic defensive shadings are now the rule, often with one to three key players, rather than a whole team, shifting toward one side. Defenders are popping up where they have never been seen before.

Opposing outfielders, for instance, play Baltimore's Al Bumbry to hit the ball down both foul lines. Enemy shortstops will practically stand behind second base when the Orioles Ken Singleton bats lefthanded, while everyone else plays straight away.

With the growth of charting hitters, teams like the New York Yankees in the 1976 World Series will use scouts in the stands with walkie-talkies to position outfielders during important games.

The most spectacular shifts, however, are saved for the finest hitters. Those extraordinary batting talents, like the shifts that work against them, are not the product of any era but of the panic that men like Rice inject into their foes.

The Ted Williams shift, the most famous, if not the first, of the tilted alignments, was sprung by Cleveland Mangaer Lou Boudreau in the second game of a doubleheader July 14, 1946.

Williams' three homers and eight RBI in the opener was the sort of bludgeoning necessity that turns even baseball managers into mothers of invention.

The perhaps apocryphal lore of that afternoon says thet a midget in the crowd seeing only one Indian on the entire left half of the diamond, borrowed a glove and scampered into the vacant outfield, then rapidly dashed off.

Variations of the Willaims shift against lefties like Willie McCovey and Boog Powell have always been intrinsically better than shifts against right-handed batters like Harmon Killebrew and Greg Luzinski.

The left side of the field can be totally vacated, begging the southpaw power hitter to slap a gentle single in that direction, while clogging all his extra-base avenues toward right.

However, the right side of the field can never be completely cleared. Somebody's got to play first base or else all those infielders packed to one side to grab hot smashes don't have anywhere to throw the ball.

After all, half the purpose of the shift is the psychological distraction of presenting the feared batter with a totally vacant field.

That challenge, that bluff, that concentration-destroyer, that pressure-builder is only at full effect against a lefthander batter.

But even the shift against a righty, which often seems to be hedging its bets because of the first baseman and the right center fielder, has much the same eroding effect.

If the slugger beats the shift with a soft single, he has sacrificed his power. The defense has, in one sense, won. If he blasts into the shift and a hit is stolen, the defense has won totally. The hitter feels persecuted.

If the batter defies the shift and gets a hit through it, even his mates may look at him as though he were living in a stubborn fool's paradise.

And, if the hitter homers, the shift was immaterial.As O's batting coach Jim Frey says, "Shifts got nothing to do with home runs. They won't let you play in the parking lot."

The beauty of the shift is that it attacks a hitter's most vulnerable part: his mind.

"Most shifts are only used when no one is on base," says Frey. But even that can be approximately half a man's at-bats.

And most shifts are used against torrid hitters. Rice had slugged 1,069 in his last 11 games. Clearly, offering him a single, at most, against the shift is a bargain for the defense.

The venom in the shift is its offspring: the slump. "Whenever you're hitting well," said Frey, "the outfield looks empty. When you're going bad, it looks like 20 guys are having a picnic out there."

The shift helps contribute to that picnic atmosphere. A few robbed line drives are enough to make even the best batters start to work too hard. "I'll rip it through 'em," says the shift victim. Or else, he changes his natural, pull-hitting swing, and throws a wrench into his own engine.

The biggest casualty of The Shift in the '70s has probably been John Mayberry. For nearly three years, he was confounded by a three-headed enemy: The shift, the Royals' big park and the constant suggestions of Royal brass that he stop pulling everything. Finally, after a 300-game slump, he was traded to Toronto.

On a smaller scale, all the refinements in defensive stratagems in the '70 have had a similar underlying element of psychic warfare. Any defender who seems out of place preys on the hitter's mind. "Why is he there? I'll cross 'em up. Have they figured me out?" Those and other netling thoughts fly through the mind.

Sometimes, the shift loses. McCovey once laid a two-base bunt down the left-field line that scored Willie Mays from first base. Williams went on a left-field campaign in '48 and, by Red Sox count, had 70 of his 188 hits to left.

However, the sense of mystification and foul play that Rice's first reaction is the typical and lingering response of the batter whoe charted tendencies have led to that loathed and unorthodox defense.

"I've only seen one player who was immune to a shift," said Frey. "A guy named Johnny Kropf in AAA was such a dead pull hittter that he couldn't even get the ball to stay fair.

"He hit so many line drives into his own dugout that his teammates hid in the runway when he was up. Johnny used a closed stance and a heavy bat outside fast balls foul.

"If they'd moved that chalk strip 30 feet, he'd be in the Hall of Fame today."

But how did that beat the shift?

"They wouldn't let us shift when we wanted to against him," said Frey. "I was a right fielder. I wanted to play him a foul territory, but the umpire said it was against the rules."