It wasn't bad enough that the Detroit Tigers had to prevent the Baltimore Orioles from defending their world championship this season. Now, the Tigers don't even have the common politeness to help the Orioles finish second in the American League East.

The Tigers thumped the Orioles, 9-2, this evening as Dan Petry won his 17th game with 6 2/3 innings of solid work. To add insult to injury, the Tigres also ended Eddie Murray's 22-game hitting streak, a mark that had tied Doug DeCinces' team record; Murray walked twice and tapped back to the mound twice. For figures freaks, DeCinces streak extended over two years.

Detroit's major damage came in a five-run fifth inning when six consecutive two-out hits scored all the runs. This genuine rarity came against loser Bill Swaggerty and reliever Tom Underwood.

The barrage, which brought groans and boos from the crowd of 25,193, featured singles by Alan Trammell (RBI), Kirk Gibson, Lance Parrish (two RBI), Darrell Evans, Ruppert Jones (two RBI) and John Grubb.

The Tigers, who lead Toronto by 11 1/2 games and the Orioles by 14, also got back-to-back homers from Evans and Larry Herndon to start the seventh off rookie Mark Brown.

The greedy Tigers added two unearned runs in the ninth as the Orioles had the indignity of watching their 1983 most valuable player, Cal Ripken Jr., make two errors in the inning on fairly routine plays. A tired-looking Ripken, who has not missed a game in two seasons, is one for 22 with seven errors in his last 11 games.

After the last pitch, Orioles general manager Hank Peters turned to his wife and said, "What an ugly game." Apparently, that's also what owner Edward Bennett Williams and his guest, AL president Bobby Brown, thought, too; they left early.

This was the evening when even Tigers Manager Sparky Anderson had to admit that the AL East race is over. "This is the longest season I've ever had since I managed. We started 35-5 and everybody said, 'This baby is locked away. It's over.'

"Well, I knew it wasn't over . . . I know how people turn and I know what direction they turn. They'll turn toward me . . .

"This has been my most satisfying season. Some people (in Cincinnati) fired me for winning 92 games. I went somewhere else and won. Maybe I can win."

This season, the Tigers have shown a remarkable aptitude for putting upstarts in their places. That's to say, every time the Tigers need to win a game to impress their superiority upon their pursuers, they darn well do it.

Last weekend, the Tigers swept three games from Toronto to put an end to any of the Blue Jays' fantasies.

"We've gone flat twice this year -- once before the all-star break and once in August. We just couldn't get people to move right," said Anderson.

"But you gotta give this team credit," he said. "When it matters, they kick it right in the rear and go. They win right when they have to. They don't leave no doubt."

This evening, the Orioles got the full kick as the Tigers amassed 16 hits and ran the bases with total (and justified) disrespect for the Orioles' outfield play.

The highlight came when bumptious Kirk Gibson scored standing from first base on a long single to right center.

Gibson, with his football background, has no real sense of baseball dimensions and this leads to some wonderful novelties; by running full speed and ignoring staid conventions -- like coaches -- he bends the normal definitions of base running. In short, he is both the stupidest and the most exciting base runner in baseball.

The entire Orioles' offense, such as it was, came from Rick Dempsey, who had a homer and an RBI double, both off Petry.

Dempsey, who has a career-high 10 homers, seven in his last 20 games, says, "I've moved up on the plate, opened up my stance, changed my hand position and I'm tryin' to hit every single pitch out of the park.

"They say you can't hit that way, but I've never felt so confident."

Dempsey, squeezing a hand strengthener as he left for home, was asked, "Why didn't you think of this 15 years ago ?"

"I'm just thankful it's happened once in my life."