It ought to be illegal to be as lucky as the Baltimore Orioles were tonight in their 5-2 victory over the Chicago White Sox.

Ken Singleton was lucky that it was the White Sox playing defense against him tonight, instead of some competent defensive aggregation. Against the New York Yankees, he might well have had just one hit. Against these Sox, who overran, underran and totally missed his flies and grounders, he had four hits in four at bats for the second straight game, raising his batting average to .512 (21 for 41) and extending his streak to eight consecutive hits, tying an Oriole record.

Just as lucky was starter and winner Scott McGregor (1-1) who gave up 11 hits in 8 1/3 innings and admitted that, "I never had anything all night except a changeup. That one pitch saved me. I must have set a new record for junk."

Equally fortunate was Earl Weaver who, in the late innings, seemed to be in a managerial sleepwalk.

He allowed McGregor, who has a history of spring elbow problems, to stay in the game for a staggering 137 pitches -- far more than McGregor would normally throw in a warm-weather complete game. However, the left-hander showed no ill effects and may now have found the beginnings of that mysterious thing called a pitching "groove" that only comes after sufficient work under game conditions.

Weaver also ended up looking like a genius after as dubious an eighth inning as he has ever managed. The Birds came to the plate with a 3-2 lead and a desperate desire to get an insurance run for the shaky McGregor. Terry Crowley opened with a walk that completed a perfect night for the Crow: three walks and an RBI single in the third inning. Normally, a swift pinch-runner would be substituted for the sluggish Crowley; Weaver had a plentitude of such options, but did not take them.

After Doug DeCinces singled, Dan Graham, who had ripped a solo homer over the 387-foot sign in the second inning, sliced a single to left that moved the lumbering Crowley no farther than third. Weaver then had another choice: whether or not to pinch-hit a lefty for Gary Roenicke against Sox righty reliever Lamarr Hoyt. Again, he went against every sort of conventional common sense, letting Roenicke hit; he popped up.

This left the bases-loaded, one-out rally in the hand of Mark Belanger who, at that moment, had three hits in 31 at bats in '81.

When the count reached 1-2 on Belanger, few in the crowd if 11,774 anticipated anything except a whiff. After all, only the day before Belanger had snapped a streak of six consecutive strikeouts with a pop that almost reached the outfield grass.

However, the resident genius of 33rd Street had another idea: the two-strike suicide squeeze.

The far-from-swift Crowley, totally ignored as he led off third, broke for the plate. Belanger, as deft a bunter as he is poor a hitter, laid down a perfect bunt toward the mound on a mean fast ball, tailing down and in, that might have hit him in the knee if he hadn't gotten his bat on the ball.

The primary beneficiary of Chicago's defense was Singleton. With two men on and none out in the third, he hit a high pop down the left field line that any of three Sox could have caught while standing completely still.

However, the left fielder, third baseman and shortstop only had eyes for each other as they raced into foul territory, then engaged in a hilarious three-way collision. The crowd's joy was total when the ball landed a good 15 feet behind them, kerplunking a foot fair for an RBI double.

"When you hit a popup and get a ground rule double," said Singleton, "you know you're in a groove."