One day, George Steinbrenner says he's "upset." The next, he's "disappointed."

"Several of us have been playin' like dogs," says Reggie Jackson, "and I'm one of 'em."

"I sure hope we come out of this soon," says Dave Winfield. "We're definitely not producing."

"The bright spot?" growls veteran Lou Piniella. "There's no bright spot to going home and not being able to sleep 'cause you keep thinking about everything you're doing wrong. Maybe I should have retired after last year." e

"We're forcing. We're swinging at bad balls. It's a real team slump," says Coach Charlie Lau. "Everybody's got the old home run complex."

Manager Gene Michael, in past years a loquacious observer and occasional wit, is so generally uptight and hypercautious that if you ask him what day it is, he'll check the calendar, then say, "I'm not sure. Ask somebody else."

You'd never guess that the Yankees, entering tonight's game against Oakland, were just one victory behind the pace they set last season when they led all of baseball in victories with 103.

The Yankees have been in an offensive wilderness for five weeks. On opening day they scored 10 runs on 14 hits. For the next 29 games, until tonight, they flailed their bats in vain. But, finally, with nine runs and 13 hits in a 9-5 victory over Oakland tonight, the Yankees showed the first glimmerings of awaking from a nightmare team slump.

The second Yankee hitter of the night, Bobby Murcer, hit a two run homer and the next to last, Reggie Jackson, hit a three-run homer off reliever Jeff Jones. It was the first cause for Yankee enthusiasm at the plate in well over a month. Only time will determine if this is a New York oasis or a cruel mirage.

It's not easy to be a Yankee. This is a team that, in its eighth year under owner Steinbrenner, has perfected a tenor of mildly grumpy dissatisfactio in good times that spikes into full-scale irritability when things really go bad. Nothing less than a perpetual 10-game winning streak, plus a 10-game lead in the standings, is enough to allow this team to smile.

Maybe only a team as saturated with talent and as burdened with expectations as these Yankees could be so discontented about a first month of the season that, by normal standards, has been very acceptable.

After their victory over Oakland, the Yankees had won 18 of their first 31 contest.

Nonetheless, all the New Yorker worries were not the product of idle fancy run amok. Nothing disturbs a team's mood more than a wide-spread batting slump. Since at least 15 of every club's 25 members are players, not pitchers, and since players tend to be more extroverted and emotional than pitchers (at least, according to baseball myth), it is the mood of a team's hitters that usually dictates whether a clubhouse is sweet or sour.

At least that would account for the Yankees' current surliness.

Eleven of New York's 16 players (including six of nine starters) were hitting .202 or less.

The Yanks as a group were batting .224 and their run-production pace was so low that, at the current rate, New York would score 227 fewer runs than it did in '80. In only 10 of 31 games has New York scored five runs or more.

With men in scoring position, Jackson is hitting .207, Bobby Murcer .200, Oscar Gamble .174, Graig Nettles .048 (1-for-21), and so forth.

In addition, three Yank regulars are out with injuries: Rick Cerone (expected back in "early June" from a broken thumb), Bob Watson (just placed on the 15-day disabled list with a thigh-muscle injury, expected to be out longer) and Jerry Mumphry (day to day with a bad thigh).

To call the Bronx Banjos "concerned" would be an understatement.

"The pitching has been terrific (2.88 ERA, third in AL), but you wonder how long they can keep going," said Steinbrenner, whose minions are 6-7 in May and have let the pesky fowl of Baltimore get two games ahead of them in the loss column.

Reggie Jackson says, with common sense on his side, "I'd be a lot more worried if I knew a lot less about baseball. Willie Randolph and I may hit .190 for a month, but we're not going to hit .190 for no full season."

However, the sage Lau also grasps a piece of the truth when he says, "We've probably scored 40 to 50 less runs so far than you'd expect of us. Sure, we're bound to hit better. But are we going to get those runs back somewhere down the road, or are they gone? I say that we'll get 'em back in a hot streak. But I'd certainly rather be 50 runs ahead of a normal pace."

The Yanks are hitting even more homers than they did last year -- 36 in 30 games, compared with 189 in 162 games in '80. That can be part of the problem. "You can't try to hit a six-run homer," says Lau. "Everybody wants to help too much with one swing. Homers can lead you astray."

If anything, the Yankees have been fortunate to build such a solid record in a season when, so far, they have not solved any of their more essential problems.

The jury is now out on three positions in the Yank lineup.

Catcher Barry Foote has hit five homers (all with the bases empty for five RBI) since being released from Cub bondage, but he is poor defensively; base thieves are 23 for 32 against New York. When Cerone (.167) returns, will he be the 85 RBI man of '80 or the .230s hitter of his previous years?

At third, Yank management still agonizes over The Aging of Nettles. "Every spring, they look at me to see if I'm creaking," says the Magic Dragon, "and every spring they seem to look harder."

Finally, New York must worry about the power position of first base. "Spencer worries me most," says Steinbrenner. "He said that all he wanted was to play first base for a month against right-handed pitching and show what he could do. I hope what he's shown us isn't what he meant."

"When you're hitting .100," grumbled Spencer, "there's nothing to say."

Season after season, the Yankees seem to illustrate one broad philosophical question about the game: does a team play better or worse when it is under constant external pressure, much of it unnecessary? However, because the Yankees' depth of ability is so great to begin with, it is difficult, if not impossible, to come to a definitive conclusion.

Winfield went through that New York culture shock in spring training. "It was different than any other spring of my life," says the $25-million man. ""The atmosphere was like the playoffs from the first day of March. You're expected to win from the first exhibition game and nothing less is satisfactory. At first, I may have tried to overcompensate and tried too hard. But I'm getting used to it."

That, in a capsule, is what makes the Yankee situation unique, and also so hard to analyze.

The Yankees are baseball's highest priced act and they also perform on the highest wire. Without a net. When they sputter, the nation's biggest city screams, "Choke!" When they soar, that same city asks, "Can't you go higher than that?"

That these Yankees of the spring of '81 can play so creditably, yet feel so much pressure and, relatively speaking, enjoy so little pleasure, is one of the sad but enduring paradoxes of baseball's era of wealth.