Over the months of a long season, a baseball team with sharp eyes can steal a few extra wins. And a team with tight lips can prevent giving a few away.

That was the case tonight as the swift but unobservant Kansas City Royals lost, 5-2, to the secretive Baltimore Orioles.

For two days, while hobnobbing with the Royals, the Birds have kept mum about the hamstring that pitcher Steve Stone pulled while running in the outfield before their home opener.

"If they'd known, of if they'd figured it out, they probably could have bunted Steve out of the game in one time through the batting order," said one Oriole.

Instead, Stone, who could throw 86 mph but couldn't move faster than a walk, three 101 pitches tonight, shut out the Royals for the first seven innings as his mates built a 5-0 lead, then limped to a shower so reliever Tim Stoddard could get the final five outs for a save.

In addition to Stone's injury, Oriole third baseman Doug DeCinces woke up this morning with inflamed tendons in his ankle and could not play. Rookie (Flat) Floyd Rayford had to make his major league debut at third.

"A rookie at third and a pitcher who can't move," said DeCinces, "and the fastest team in the league never lays down a blunt all night. We certainly appreciate it."

The O's had conventional heros -- Eddie Murray with a two-run homer, Al Bumbry with a bases-empty blast and Pat Kelly with an RBI triple.

But that's not what had the O's giggling as the Royals limped out of town after being swept in a three-game series by a total score of 19-5.

"It's been like the CIA around here for two days," said Rabbit Miller, pitching coach. "We've even been swearing ball boys and security cops to secrecy."

The Royals could have guessed. But they were asleep at the switch. Their seventh batter of the night hit a grounder to Eddie Murray's right. Stone, one of the game's most alert pitchers, barely budged off the mound, forcing Murray to sprint to the bag to beat the runner.

The Royals never wondered why. Nor were they suspicious that chubby Rayford was creeping in on every left-handed hitter.

"We knew he was playing awful close," said dejected Royal Manager Jim Frey, the former Oriole coach, "but we didn't know about any hamstring pull."

The Royals, who stole 207 bases last season, left town with zero steals, zero hit-and-runs and zero bunt hits.

Still, the best long-range news for the O's was not that they had been successful hiding Stone's leg, but that they discovered his arm.

Memo to all ailing Baltimore Oriole starting pitchers: Get well quick, because Stone is after your jobs again.

The O's had little choice but to start the injured Stone tonight, with both Dennis Martinez and Scott McGregor still disabled. But, after watching Stone's best fast balls as an Oriole tonight; both are likely to heal in a hurry.

"I'm ready to start on Sunday," Martinez announced.

"I think I'll be ready for next Tuesday in New York," McGregor said.

Baseball's best-known miracle cure still is competition.

And the panacea for every pitcher, as Stone demonstrated on this comfortably chilly evening before 7,166 fans, is a comfy lead early. The O's gave him that with two runs in the first and two in the fourth off Rich Gale.

Those four runs equaled the number Baltimore had scored off the menacing 6-foot-7 right-hander in his previous 23 1/3 innings against the Orioles. This night, they played on the giant's weaknesses: temporary loss of control.

In the first, after throwing eight balls in nine pitches, Gale laid a fast ball down the pipe to cleanup man Murray. Murray, who went six-for-nine in this series, deposited the cripple pitch into the Kansas City bullpen 410 feet away for two runs.

Murray was back in the fourth, singling through Gale's skipping feet, then scoring as right fielder Clint Hurdle misplayed Kelly's drive off the wall in the corner into a comic three-bagger.

With the infield drawn in, John Lowenstein undressed second baseman Frank White with a vicious one-hopper into right field.

Encouraging signs kept cropping up all night for the Orioles, who, after losing their last eight exhibitions and starting the season by losing three of four, seem to be turning a corner.

Bumbry, who has been working on his undiscriminating batting eye and already has five walks, uncorked one of the longest of his 33 homers as an Oriole, a 400-foot shot to right off Gale in the fifth.

Rick Dempsey, whose slugging average reached .842 after a first-at-bat hit, helped Stone by gunning down a stealing White in the first inning just one pitch before George Brett doubled.

Told of his remarkable slugging percentage, Dempsey showed interest. "Yeah?" he said. "How do you figure a slugging average? I don't think I ever had one before."

To conclude the pleasant night's work, Stoddard finished matters expeditiously after a two-run triple by Brett had knocked out Stone with one down in the eight.

"We thought we had Brett confused," Dempsey said, aware that Brett has a .364 seven-season average against the O's. "All series we've been throwing him fast balls down the middle and he's been getting himself out. But I think he figured it out tonight."

Nobody figured out Stoddard, whose fast ball was clocked at 90 mph and whose slider was hitting the corners.