If Dashiel Hammett had created a baseball player in the Sam Spade image, it would be Graig Nettles.

The New York Yankee third baseman is baseball's innocent-at-heart cynic, its cryptic quipper, its anti-hero with absolute allegiance to the unwritten rules of the clubhouse.

Nettles even resembles Spade the way Hammett describes him in "The Maltese Falcon," a lean, supple, sardonic, fair-haired 6 footer with a satanically mischievous face.

The Gold Glover who robbed the Los Angeles Dodgers in game three of this World Series with two stunning fielding plays is no image-conscious fellow. The private eye's hard-boiled contempt for the world's shallow goodwill fits him well.

Nettles would be the samus of fiction who crushes out his cigarette on the district attorney's mahogany desk. This is no handsome hero out of a children's baseball tale.

Nettles has a Gold Glove and a home run title. He owns the big league season records for assists, double plays and chances per game for third baseman. Assists are the perfect barometer of a third-sacker's range, and any way you slice it, the stats say no one has ever equally Nettles' range. For one season, five or nine, Nettles' assists and total chances leave Brooks Robinson and all others behind.

Yet Nettles, despite hitting more homers than any other American League except Reggie Jackson over the last five years, has no fan club, no wide following. He wouldn't want one any more than Spade or Philip Marlowe would.

Pride, to Nettles, is a uniform dirty on all sides and a line of fine print that says he averages playing 156 games a year, in good health or in pain.

Like Spade, Nettles in proud to combine toughness with humor, a touch of larceny with a strong notion of basic decency.

If it takes a tiny time capsule to help him play in pain, then so be it. If he finds a useful illegal bat - like one that once shattered and had six Super Balls bounce out of the barrel at home plate - then that's the way its going to be.

And if somebody else starts a fight, he'll be the first to try to finish it. In a 76 brawl with Boston, he retailiated for a Bill Lee knockdown pitch by dislocating the hurler's shoulder. In the 77 playoffs, he answered a spikes-high slide by Kansas City's George Brett by trying to kick Brett in the head while he was down, then jumping on top of him as the benches cleared.

Sir Galahad, Nettles ain't. He is an infielder in a land of spikes. On Billy Martin's bench, Nettles was the old-style, guard-your-ego-in-the-clinches kind of bench jockey.

Yet Nettles, like Spades, is the first to stand up for a friend, the first to tell the millionaire boss where to head in, the first to puncture a ballooning ego with a nettle.

"In one year, Sparky Lyle has gone from Cy Young to sayonars," says Nettles. "It's not his fault he disappeared. This club, and that means George Steinbrenner, disappeared him. They had him warning up in the ninth in our Boston playoff game. You know, 'Bail us out, Sparky. No hard feelings.'

"Well, the way they've used Sparky and abused him this year after all he's done for 'em, I wouldn't have blamed him if he'd told them to shove it.If he'd come in and thrown the ball over the grandstand, I wouldn't have blamed him.

"If it can happen to Sparky, it can happen to any of us. Next spring, may be George'll decide to bring in a new third baseman and make me a pinch hitter. Who knows? I'm 34. That must mean I can't play any more."

In any clubhouse, there is easy, glamorous publicity and then there's the tough kind. Justas Jackson is the master of hogging headlines. Nettles is just as adept as dodging them. He considers it part of being a team player. But when it's time to take a fall for a friend, or for the club, Nettles opens his mouth first.

Nettles hides in the woodwork until it is time for the clutch defensive play, the late-inning home run or the snappy one-liner. Then he returns to his camouflage. He ranks with Hal McRae and Fred Lynn on baseball's list of frumpy jean-and-sneakers dressers.

The player they call "Puff the Magic Dragon," the guy whose license plate says "E5", is seldom hounded for autographs. Who wants the signature of the fellow who looks alike he's heading for the lanes to bowl a few lines?

Few players are as feared in repartee as is Nettles. He has a habit of telling the truth.

"Why is the bus stopping?" he will say. "Are we stopping to get batteries for Lemon's nose?"

"Well, there he is, the comeback player of the year," Nettles says to Yankee captain Thurman Munson, who keeps saying he wants to be traded home to Cleveland. "Thurn said he wasn't coming back this year, but here he is."

"Hey, Reggie, how are they going to package your new candy bar?" said Nettles to Jackson last year just after Jackson was benched for dogging it on a fly ball. "I hear they don't come by the box but by the loaf."

In the aftermath of his brilliant World Series plays, the packed Yankee Stadium crowd gave him an ovation that forced two cap tips. Nettles enjoyed it, was glad to get his due. But that you-can't-fool-me smile played around his lips. "These people just think I learned to play third base in the last three years since I've been with a champion," he said. "Nobody raved when I was in Cleveland. All fans are front-runners. You're out to impress your teammates and the other players. That's all that matters. You want to leave something for them to remember you by."

It is part of Nettles' code never to exaggerate his skills, or let others embellish them. In his heart, never having seen himself play, he does not think he is a good as Brooks Robinson.

"It's compliment to be mentioned in the same breathe with Brooksie," he says. "We're kinda alike. We weren't afraid to get our uniforms dirty. Neither of us were fast but we were quick. Our arms weren't strong but they were accurate. The big difference is that I've got more hair than he does . . . but not by much."

Slowly years late, Nettles' wit, his glove and his power statistics are beginning to get their data. Far from fearing that his reputation will never catch up with his deeds, Nettles prefers to be slightly undernoticed. "I'm comfortable this way," he says.

He would just as soon not let hitters know that he has revolutionary ideas about playing his position - stationing himself further left and deeper than any man before him.

"I'm certain that five balls go through to your left for every one that goes down the line," said Nettles. "Maybe I just think everybody else has played the position wrong."

Nettles has kept equally unusual hitting theories to himself. "Batting averages are bunk," he says. "RBIs are the thing that matters.

"If I give up two at-bats to sucker a pitcher into throwing me the pitch I want with two men on, then I'm going to do it. When I'm up with no one on base. I look for the home run. A single then is just average-padding."

So Nettles goes to the plate like a gambler, swinging at occasional first pitches, guess-hitting, o waiting for a "cripple" pitch on 2-0 or 3-1. "My hitting is gravy, anyway," said Nettles, who after, hitting 69 homers in two years, accepted a demotion to eighth in the lineup without a word.

"Maybe I'm the only one that knows it, but I save more runs with my glove that I drive in. That's where I can affect the game and help my pitcher every day . . . somebody had to swallow his ego an bat eighth," said Nettles, grinning. "So why not a home run champ?"

Like that Maltese Falcon, Nettles is a hard bird to know. But under the implacable exterior lies many a jewel.