This is an invigorating moment for the thinkers of sport, for anyone who cares about the whys of winning and losing.In perhaps no other week in no other town have two major professional teams offered such stark contrasts as the Orioles and Colts.

The darling Birds sit on the loftiest perch in baseball, or until Nolan Ryan takes the mound in the American League playoffs here today. The despised Colts cannot even play a game without stirring bile.

Sunday, the Colts lost for the fifth time in five weeks. As is their luckless fashion, it rained -- and the field they left the Orioles is a cleat-marked disgrace, every few feet a potential land mine of bad hops.

The Orioles' new owner, Edward Bennett Williams, is the essence of intelligence and urbanity. The Colts' owner, Robert Irsay, is a bumbling clod who made a fortune in airconditioning and a fool of himself in sports.

One remarkable fact emerges from any close look at both teams. In two years, they have come full cycle. In 1977, it was the Colts everyone here was toasting, the Colts who were seen as a budding dynasty, the Colts with the organization that could cope with the dizzy new period of uncertainty in sports.

The Orioles were the team playing to more empty seats than customers, the team getting ripped apart by free-agentry, the team surely about to leave town although the owner was not openly playing one new territory against another.

Two athletic years are much longer than two real-world years, in terms of the important tools -- arms and legs -- of the business. In Baltimore, they have shown that fine teams can become excellent in a hurry and that excellent teams can become impotent even quicker.

The rise of the Orioles and the fall of the Colts can be traced to one basic thread: how their on-the-field leaders and off-the-field executives performed with the lifeblood of their sports -- players.

"I know what coaching is all about," said John McKay, whose Tampa Bay team lost its first 26 games and now is the only unbeaten team in the NFL. "It's players."

"In winning with any ball club," the Orioles' Earl Weaver said today, "it's selecting the right players. Strategy doesn't have a lot to do with how many games you're going to win. You win pennants in December, the off-season.

"Getting players who can perform the basic fundementals and selecting them, getting guys that can sit on the bench and then go up and hit after not playing for three of four days, selecting the right pitchers on given days, that's what goes into winning.

"We broke the (Oriole) home-run record and led the league in pitching this season. That's what me and Mr. Peters tried to put on the field. And they justified our baseball judgment."

That baseball judgment was in question two years ago, for the Orioles had ended a 97-victory season and tie for second place but lost enough Reggie Jacksons, Don Baylors and Bobby Grichs to finish fourth in the American League East the next year.

The Colts, meanwhile, had won the American Conference East championship for the third straight season in 1977. They were a relatively young team and Bert Jones was at least the third-best quarterback in football. Ted Marchibroda was called a genius. Weaver was derisively called Bird Brain.

"If you've got a future superstar in, say, Eddie Murray, you can afford to let, say, Reggie Jackson go," said Oriole third baseman Doug DeCinces. "And if you've got a Rich Dauer, you can let a Grich go.

"There was a time when players were stockpiled in the minors. I played 4 1/2 years and only finished out of first place once. But from this point on, we can't continue that sort of thing, to let a (Don) Stanhouse go, 'cause there isn't that wealth of talent in the minors now, or at least the high minors."

Lately, nearly every player moved by the Orioles has been spectacularly successful, from trades with the Yankees (that brought Scott McGregor, Rick Dempsey and Tippy Martinez) and Expos (that brought Stanhouse, Ken Singleton and Gary Roenicke) to the development of Murray, Dennis Martinez and others.

The Orioles have proved that teams with brilliant management can win while still in transition, for hardly andy team in any sport has undergone more changes in recent years. The Colts have demostrated that a few mistakes in personnel can create nearly unmanageable problems.

Marchibroda still is a superior football coach. He took good players and won almost 75 percent of his games his first three years with the Colts. The major reason for the 5-16 record since, outside of the injury to Jones, has been Marchibroda's trying to be more than a coach.

He apparently assumed too much control after winning that battle with General Manager Joe Thomas just before the 1976 season, for the Colt drafts the last three years have been awful.

Thomas had a flair for personnel, having drafted most of the players who helped Marchibroda achieve such immense success. But his final draft, the year Marchibroda arrived, was a bad one. The three since have been equally dismal.

"He (Marchibroda) is the draft," a Colt source said. "That was the biggest jewel (in his struggle with Thomas)."

The jewel no longer shines. In four drafts, or a total of about 50 players, the Colts have developed only three starters, tight end Reese McCall and linebackers Sanders Shiver and Barry Krauss.

When their two strong areas were wide receiver and the defensive line, the Colts' top choices Marchibroda's first year (1977) were a wide receiver and defensive lineman. That wide receiver was Randy Burke. Passed over by the Colts that year were Wesley Walker and Tony Hill.

There have been an inordinate number of injuries to the Colts, to offensive linemen George Kunz and David Taylor, in addition to Jones. A splendid defensive lineman, John Dutton, is sitting out the season in a contract huff.

And Colt fans are booing the team with the same verve with which they once embraced them. They are furious over Marchibroda's no-frills offense, singing "Goodbye, Teddy" at the most recent game. If the boos are proper, they are for the wrong reasons.

Baltimore fans are among the few in the country who can celebrate and commiserate in the same park.