The Baltimore Orioles feel as though they are caught in the middle of somebody's cosmic joke.

After this evening's burlesque 5-2 loss to the Boston Red Sox, Baltimore's fifth consecutive defeat after seven straight victories, the Orioles have no idea how to feel about themselves.

Are they a first-class club with realistic World Series dreams, as they looked to be just five days ago when they were hitting sudden-death homers and winning game after game by one run? Then, the Orioles were full of laughter, practical jokes and home-plate celebrations.

Or are they the snakebitten, prat-falling comedians who brought their Royals Stadium act back to Memorial Stadium this evening and performed it for the shocked displeasure of the home folks. Now the Orioles take long, hot showers in solitary silence, then reappear in their locker room, a fraction of their frustration steamed away, to murmur in monosyllabic monotones.

The most fascinating twist of the Orioles' torture is the way the schedule sent them to Kansas City at the very juncture in the season when they had finally regained some of the elan and spark that they showed in 1979 and '80. No nefarious practical prankster could have played a dirtier trick.

Last night, the Orioles continued all the horrid habits of nervous fielding and overanxious hitting that infected them in K.C.'s Emerald City.

They proved they could look every bit as amusing on defense on plain old-fashioned grass as they do on turf. Boston's margin of victory was built on an unearned run in the third, a sacrifice fly to shortstop in the fifth and a routine fly to left in the sixth that fell for an RBI hit.

One of the more misleading statistics in the American League is that Baltimore has the fewest errors (63); usually, the Orioles are steady and competent afield, but when they go sour, there's no denying that they can really stink out the joint. This evening, before 25,010 witnesses for the prosecution, Scott McGregor (12-8) was knocked out and defeated as much by the work of his guilty teammates as by the Red Sox, who moved back into a first-place tie with Milwaukee.

While McGregor was watching a booted grounder, a wild throw, a botched foul fly, two squandered double plays, an overthrow and another hit on a usually routine fly ball, starter and winner John Tudor (7-8) was observing his fielders as they roamed far and wide to shag liners.

When Tudor tired with one out in the seventh, after allowing only a homer to Eddie Murray in the second, reliever Bob Stanley finished the job, permitting only a sacrifice fly to the first batter he faced, John Lowenstein.

It's ironic that the last time the Red Sox played the Orioles, the month was April and the Birds were working on a masterpiece of a nine-game losing streak. Although the Orioles still have the best record in baseball since May 13th (43-28), it's unlikely that now, more than three months later, the Red Sox can tell the difference in the team.

Since the All-Star Game, the Orioles are 10-8 and have gained a game in the standings, from 4 1/2 to 3 1/2 behind in the AL East. However, in that time, they have been on a stability-shattering roller coaster ride.

"Look at the whole picture, and we're not bad off. Two games behind in the lost column with two months still to play . . . heck, that's nothing," said catcher Rick Dempsey. "But it doesn't feel that way."

Said Ken Singleton: "It would be a whole lot easier on our nerves if we'd played the last 12 games 7-5 by winning two, losing two, winning one . . . These streaks are hard to take."

If baseball measures anything, it is emotional resiliency. The Orioles' collective sanity is being sorely tested.

For starters, third baseman Floyd Rayford was zero for four with three strikeouts, made an error, cut in front of Cal Ripken and helped distract him into another error, and, finally, turned a double-play ball into a forceout.

Benny Ayala got two singles but proved he can cause trouble when he ventures into the outfield; playing so deep it looked as though he was guarding the bleacher exits against Martian invaders, Ayala let a fly ball by Jerry Remy fall in front of him for an RBI hit. On another occasion, Ayala, standing in fair territory, missed a fly that dropped two feet foul. Only the fact that he missed it entirely prevented its being a double.

Dan Ford had his nightly 0-fer and overthrow of a cutoff man.

Ripken was forced to make a sprinting, over-the-head catch of a pop with a man on third because Ayala was still way out yonder making sure no one tried to steal the numbers off the outfield fence. Ripken, however, slipped and couldn't throw out the runner; thus, sacrifice fly to short.

Does Ripken feel comfortable at short yet? "At times," Ripken said. "At times it feels different . . . In Kansas City, I felt helpless, like I didn't have any range at all."

But it's tough to be 21 and leading a shaky infield in a pennant race.

In these straits, the Orioles desperately try to be wise--a contradiction in terms. "I know we're still as good as we looked last week," said Singleton. "At least we're not going backward 100 miles per hour. Everybody seems to be waiting for us. Right now, everything the other guys hit falls in, like they threw it there, and our rockets are going right at people.

"I believe that you can make your own breaks in this game, if you just don't quit. You just gotta keep tellin' yourself that the littlest spark can start the biggest fire."

Right now, the Orioles' great fire of just one week ago is down to embers.