In an athletic subculture of self-conscious etiquette and genteel, elitist fashion, Craig Stadler--who won the 46th Masters on Easter Sunday--is the defiantly unregenerate average Joe.

Despite being in the top 10 golfers in the world for the third straight year--he now is No. 1 on the '82 money list after his $64,000 Masters prize--Stadler has no manager or agent, no major endorsements or contracts.

He's even an essentially self-taught player with no pretentious swing guru doctoring his game. "Yes, I'm probably more self-taught than anybody on tour," he said, before realizing that sounded like bragging and added, "Well, more than most . . . When my swing goes bad, I just go to the range and goof around with it (the swing) until it falls back in the groove. I play entirely by feel."

Stadler does none of the flashy $10,000-a-pop appearances and exhibitions of other stars, preferring just "eight or 10 (low-key) little things a year that I enjoy doing . . . Going to Colombia (South America) one week and New Zealand the next for $8,000 or $10,000 or $15,000 isn't in my game plan . . . I don't ask for it and they don't seem to want me . . . I haven't cared to run my rear ragged."

Stadler also hasn't cared to dress or act much like the typical touring golf pro. He lost 40 pounds to prove he could, but now has gained 30 of it back because it's more comfortable. It doesn't faze him that jokers, as he approaches the green, say, "Don't yell 'Bite' around Stadler. He might do it."

The head covers on his woods have walruses on them and the license plates on his van and his jeep say, "WALRAS" and "WALRUZ." Somebody else has "WALRUS"--correctly spelled--and won't give it up.

For years, Stadler also has refused to hide his emotions on course, tossing clubs and curses as he felt the flow of play merited. Once, playing Walker Cup in England, Stadler so offended his British caddie's sense of decorum that the bag bearer walked off the course in midround in a righteous snit. Photos of Stadler, carrying his own bag, made the English tabloids with the caddie portrayed as a minor national hero.

Though he's crusty enough not to admit it openly, Stadler likes his mildly antiestablishment stance. This is the guy who drove Southern California Athletic Director John McKay nuts by wearing jeans and sandals to play college golf matches, prompting offended letters to the athletic department about the chubby slob playing No. 1 for the Trojan linksters. Since Stadler was U.S. Amateur champ in '73, his wearing loafers on the back nine was tolerated.

On tour, Stadler horrified traditionalists by having a bag bearing the advertisement "Taylor's Steak House." Of course, if Stadler's bag had just flacked for a golf ball conglomerate, instead of trying to help out his best friend's small restaurant in Los Angeles, nobody would have hassled him.

"I took it (the Taylor's ad) off the bag for the same reason I put it on," said Stadler cryptically on Sunday after his playoff victory over Dan Pohl. "No reason at all."

With the years, Stadler has lost a bit of his outsider's prickliness. At his green-coat presentation on the practice green at sundown on Sunday, he told the Augusta National crowd, "I'll be back here to play every year as long as I can swing a club."

Even his sensitivity to fat jokes, and insinuations that he can't be a truly great golfer because he doesn't look like one, have subsided.

"That (fat) stuff depends on who says it and what I've just done," Stadler says.

Now, Stadler can even make his own one-liners. Asked if his shorter driving these days was a deliberate decision or merely the result of getting older, Stadler, who is only 28 but has a incipient bald spot, said, "I may be fat, but I'm not that old."

Others might get a tusky growl, but Stadler's friends regaled him after his victory with lines like, "Stadler got the last laugh today . . . with both chins," and "I don't want to say Craig had the Masters locked up, but when he was on the back nine (with a six-shot lead) I saw some guys in the clubhouse stitching two green jackets together."

The big shots and front-runners around sport don't get Stadler's time. Before he teed off for Sunday's fourth round, leading by three shots, his locker had a stack of telegrams from all those who wanted to make sure he remembered that they'd remembered him.

Who were these jump-on-the-bandwagon telegrams from? Anybody important?

"Don't know," said Stadler, wearing his new green jacket over blue pants. "Haven't opened 'em."

Finally, well after dark, as his victory sank in, Stadler was asked to sum up the state of his life and game--the sort of preposterous question you only get asked after you do something like win the Masters.

"I'm playing better than ever this year because I'm having a lot of fun playing the game for the first time," said the son of a La Jolla pharmacist, who, for years, fought the game as though it were his enemy. "Golf is the only thing I really know a lot about, and I guess it's the only thing I want to know . . .

"I'm just enjoyin' myself and movin' right along."