Self-pity is the bane of defending baseball champions.

Whatever blend of talent, tactics and luck takes a team through 162 games to a flag, it is generally a percarious mix, one which is often upset the next year.

Teams that grow to think of themselves as "champs" are seldom want to believe how thin their margins of advantage actually is.

So, when affairs go wrong for a team still buoyed by World Series play, the easiest and most human response is to feel sorry for yourselves, itemize your bad breaks and constantly predict an imminent return to form.

All of which describes the American League champion Baltimore Orioles. After losing to the Boston Red Sox today, 6-4, they wobble into the All-Star break with a mediocre 42-36 record and an nine-game deficit to the New York Yankees.

The O's were 59-31 (.656) at last season's break. Now they don't know whether to panic or yawn, whether to relax and simply wait for things to come right or play with redoubled animation and risk performing like Birds with their heads cut off.

The Orioles, from the 25th man on up to Manager Earl Weaver, are extremely confused. Their sincere opinion of themselves and their league standing (fourth place) are in serious disagreement. One or the other is dead wrong.

So, the Birds mutter, make obscure excuses (since they have few tangible ones) and talk about the glorious second half that awaits them.

Meanwhile, the Birds continue to make uncharacteristic fundamental mistakes, gnash their teeth, curse the fates -- and lose.

Today, it was Boston winning its third game in four in a series that allowed 117,506 paid admissions to see everything that ails the O's.

In the four days, the Birds ran the bases stupidly, twice taking themselves out of big first innings by getting men trapped off second base. Twice they faced rookie pitchers with one career -- victory each, and twice they lost.

Instead of seeing ill fortune as a challange, the Orioles -- as in the last three games of the 1979 World Series -- seem to submit to it weakly, as though it were their fate.

The worried man is Weaver, though he disquises it. Outwardly, he is still letting the "poor little old us" record play its course. Today, after getting the 75th ejection of his career, but his first of this season, Weaver came as close to blaming an umpire for a loss as he ever will.

"The (home plate) umpire's directly responsible for their first three runs," said Weaver. "We should be leading 2-0 instead we're down, 3-2, in the third inning and I'm comin' out to talk to Mike Flanagan, who oughta be workin' on a shutout."

The nature of the controversial calls is minor -- whether a bunt was fair or foul, whether a borderline pitch was or wasn't a third strike. What is interesting is how desperately the Birds look at all manifestations of good or bad "luck."

"I gotta believe that this guy (ump) Rocky Roe is better than he showed today," said Weaver. "He can't be that bad.

"But you can say that Rocky Roe has given us a rocky row to hoe," Weaver quipped.

One day it is the wind blowing home runs back into the park. The next it is a bad hop or a mean umpire.

The only root cause the O's have discovered for the malaise for which they blame themselves is a lack of power.

"We're short some home runs," noted Weaver, who builds his attack around four base power and is very worried that his club has just 62 home runs compared to 90 at this stage of 1979.

"Basically, at this point, that's the only thing that's wrong. We've played great ball for the last month (9-12 since June 1) without home runs.

"Our starting pitching couldn't be much better (with 16 complete games in the last 32). Our bullpen's so rested that I called up Joe Kerrigan from Rochester three weeks ago and he never even got a phone call to warm up until today. He must have thought he had an unlisted number," Weaver went on.

"When we get some breaks and some of the homers that are due us, then people might be calling us 'awesome,' in the second half."

That is the quai-official Oriole line: just wait . . . the real Orioles will reappear . . . a pennant race is at the end of the tunnel.

"The Yankees are playing so far over their heads it's pathetic," one Oriole said today. "Guys like Brown and Lefebvre and Murcer are hitting homers to win games. There's plenty of potential trouble in that clubhouse waiting to bubble up as soon as they hit a bad streak.

"Just wait. In September, the race'll be like this," said the Oriole, holding two fingers a millimeter apart.

"When we get two or three games back, you won't be able to buy a ticket to get into this park. We'll make last year's attendance (1.7 million) look small. Just wait."

Club owner Edward Bennett Williams listened with pleasure to this whole analysis, then said, smiling, "I'm with you."

But Williams knows all about the dangers of whistling in the dark.

"I thought we'd get at least 150,000 fans for this series. We got 120,000.

That's no good. We can't make it like this," said Williams, who recently renegotiated long-term contracts for Doug DeCines and Jim Palmer as part of an obvious club policy to raise its salary structure and commit itself to its current crop of players.

"I don't understand why the people aren't showing up," Williams added. The team is playing good baseball, yet we're drawing better on the road than at home. That's a terrible indictment."

Older baseball heads see the Orioles' quality of play a bit differently.

"We've only played good baseball sporadically all year," said Terry Crowley. "I can never remember Boston coming to Balitmore for a four-game series and making less mistakes, beating themselves less, than us. But they did. They looked good. And we didn't"

"When you fall behind in the race, it begins to seem like more things are going against you than really are," added Crowley. "Every 'would have' and 'should have' is magnified."

Two factors have mad this version of the O's more vulnerable to those "woulds" and "shoulds" -- much diminished power in the Nos. 5-6-7 spots in the batting order, and a bullpen that has gone from excellent (with Don Stanhouse ) to merely good.

Perhaps the best advice came from old Oriole Elrod Hendricks. He caught for the 1969-70-71 champions who overcame bad starts. Now he is on the coaching staff.

"You have to make your own breaks, and we haven't been doing it," said Herdericks. "You can't sit around and expect other teams to do you favors. I'm tired of listening to guys talking about what we did last year.

"We better start thinking about this year."

The 1979 Orioles had something to prove and played like it. The '80 O's have something to defend; it has made them tentative and jittery instead of bold. Their 9-14 record in one-run games is a betrayal of a long Baltimore history.

The Orioles, however, are, above all else, an eminently likeable team -- a club with, perhaps, too little arrogance.

While the Red Sox, for instance, have seemed icy and a bit selfish here. the Orioles show few signs of griping or back-stabbing among themselves.

"We watch the Red Sox -- how little feeling they seem to have for each other -- and we can hardly believe it," said Ray Miller, the Oriole pitching coach. "Skip Lockood got hit by a linedrive Friday night and he's down in the dirt gasping for breath. Butch Hobson's 20 feet away at third, looks at him, spits in the dirt, turns around and goes back to his position. He couldn't cared if the guy lived or died.

"You'd never see that on this team."

There is at least one Red Sox with feelings, nice guy Tony Perez, who sparked today's victory by driving in three runs -- with a sacrifice fly, a single and his 12th homer. He leads the league with 64 RBI.

The Orioles have won together, sharing the credit, and now they lost together, sharing the aggrivation and the mystification of it. And, like the close-knit flock they are, they have commiserated with each other and pitied themselves more than a bit.

But, now, like many a champion before them, they have reached the point where nothing less than three months of sustained intense excellence will redeem their season.