Before Game 4 of the World Series today, the Yankees were in a most unYankeelike mood. Reggie Jackson was smiling: Thurman Munson was cordial. In short, they were acting like - pardon the expression - a team.

"I'm bettin' against us," Munson joked. "We're too overconfident. Everybody knows we can't win unless we're behind or have had some big argument."

Nearby, Jackson was giving a clinic in power hitting. Seven times he swung during one stretch in batting practice and five blows landed far beyond the outfield fenses. Munson could not hit anything beyond the batting cage, but he was as cheerful and relaxed as the rest of the team.

To which the Dodgers' Steve Garvey said: "Maybe that's a good omen. They're not hitting each other. We'll lull 'em to death."

In truth, it was a 153-pound lefty with a he-man fast ball who lulled Dodger bats today, with a 4-2 victory that had the Yanks talking not only of winning the World Series, but of doing it before returning home. No one is thinking about the awful possibilities had Ron Guidry not literally turned around in midseason a year ago and given the Yankees one more chance.

"They'd sent me back to Syracuse last year, but I was driving south," he said. "I was ready to quit. I did't tell 'em nothing. I figured if they wanted me, they could find me.

"They'd been playing games with me, bringing me up and sending me down, up and down, up and down, and I was tired of it. I figured why throw my arm out just to hang around in the minors?

"I guess we were about 50 miles outside New York, in New Jersey, I guess, when my wife (Bonnie) said I ought to give it one more chance and then quit if it didn't work out. I pulled in a service station and just turned around went back. It was that simple."

Guidry has been the starting ace of the staff much of the season, with a 16-7 regular-season record and one playoff victory over Kansas City. this Series seemed very uncomplicated, although Davey Lopes socked a two-run homer and Lou Piniella jept Ron Cey from a leadoff blast with an over-the-fence catch in the fourth.

Seven strikeouts and four hits allowed were the important Guidry numbers - to go with several honest opinions.

Does he believe the Yankees with a three games to one lead are in an unbeatable situation.

"Yes," he said, "I think we [WORD ILLEGIBLE] What Guidry did with his wicked fast ball and slider was execute the simple strategy suggested by third baseman Graig Nettles.

"The key to beating the Dodgers," Nettles said, "is to keep 'em from huggin each other. What I mean is, if they're scoring runs, they're hugging each other."

The muggers beat the huggers today.

Why a fellow so naturally swift should take so long to become successful, or even to be recognized as talented by the Yankees, is a mystery. At 27, he had been in the minors most of his seven pro seasons - and had a horrid spring training this year.

"You see lots of great talent never succeed in baseball," said Fran Healt, Yankee bullpen catcher and resident thinker. "They never get the opportunity. But Ron did - and he's doing well now because of positive reinforcement.

"He pitched well when he finally got th chance (mostly because of injuries to more expensive Yankee arms), and because of it kept getting better each time. He is simply an outstanding pitcher."

It took some time for Guidry's fast ball to become lively this spring - and Sparky Lyle taught him a slider that moves downward rapidly to replace the flat one that seemed destined to send him into early retirement.

"It did not take that long," Lyle said. "because he had the good mechanics. I told him how to correct things when the pitch was going bad, and he did the rest.

"I don't thrown nearly as hard as he does. I guess if I had the sort of fast ball he has and they screwed around with me like they did with him I might have been ready to pack it in too."

Guidry is a curly-haired, soft-spoken man who seems out of place among the Yankees' outgoing egos, a fellow not given to instant public humor but who said of the bonus he received when drafted out of college, "A hot dog and a coke - a medium-sized hot dog."

He said he did not feel pressure, especially today, and is not frightened by anything except perhaps shooting himself in the foot while hunting in his native Louisiana.

"Tonight, I'll probably treat myself to a nice dinner - and maybe a couple of drinks," he said.

Does he consider himself a money pitcher?

"I'll leave that up to somebody else. I just do my job. I just want to prove I can pitch up here."

Which is in significant contrast to Jackson, who after a double and home run, two runs scored and one batted in, burst through a crowd of reporters en route to a larger interview and said: "You can love me or hate me, but you can't ignore me."