Why are the Dallas Cowboys almost always in the playoffs and the New Orleans Saints almost always in last place? Why have the N.Y. Islanders sipped champagne so often while the Washington Capitals keep crying in their beer? Why do the Dodgers and Lakers win championships while Cleveland's Indians and Cavaliers have trouble getting to .500? In a four-part series beginning today, Washington Post staff writers examine the differences between the winners and losers of professional sports.

Almost nothing is rarer than a good idea.

If there is one common denominator for the most successful major league clubs, it is an ability to conceive a simple overall idea of what sort of team is desired and, patiently, over a period of years, stick to that plan.

The exact nature of that guiding idea, or nexus of interlocking ideas, is not nearly as important as the courage to carry it forward through hard times.

Few franchises realize that no team, not even the richest, can have everything. And, that every organization, even the most consistent ones of the last quarter-century--such as Baltimore, Los Angeles, Cincinnati and the New York Yankees--have occasional bad seasons.

In baseball, the key to victory isn't creating a team without weaknesses, but constructing a club with concentrated strengths that outweigh flaws.

Even the 1927 Yankees lacked speed and the '75 Reds were short on starting pitchers. Most world champions, in fact, have at least a couple of glaring weaknesses. The '81 Dodgers had poor defense in the middle of their infield, less than average team speed and a merely adequate fourth starter.

A team is far ahead of the game if it can identify the set of virtues that suits its park, its tastes and--in these free-agent days--its pocketbook. It makes little difference that, from team to team, those virtues may be vastly different.

For instance, Baltimore Manager Earl Weaver loves "(starting) pitching, three-run homers and fundamentals," while consciously putting a lower value on team speed, depth of relief pitching and high-average, all-fields hitting.

By contrast, Whitey Herzog's successful infatuation in Kansas City, and now with St. Louis, was with--guess what--team speed, depth of relief pitching and high-average, all-fields slap-hitting.

Both team builders are eminently successful, not because either has an intrinsically better theory, but because each has a concept that suits his stadium and his club's resources.

The Orioles play in a pitching-oriented grass park where, because of short, slanted walls in the corners, outfielders can pinch the alleys. The result is that walks and sharply pulled home runs are, theoretically, the best style of offense. A line-drive, gap-hitting team, such as the late 1970s Royals, would be at an offensive disadvantage there. Their grounders wouldn't scoot through the soft infield, their base stealers would be a step slower on dirt than AstroTurf, and their doubles in the gaps would be singles or outs.

On the other hand, in Royals Stadium, the Orioles have not done well. Their long flies are just outs. And their pitchers' routine outs--those nice grounders and infield chops--suddenly become hits that open up big K.C. innings.

Almost without exception, winning teams gear their squads to their parks. The '76 to '81 Yankees were, without question, built on owner George Steinbrenner's checkbook. However, he did what many other rich owners couldn't do: he spent his money wisely. Those Yankees were based on left-handed power hitting and left-handed starting pitching, thus making the Ruthian porch in right field work to their advantage.

The recent Houston and Oakland clubs have understood that they play in, statistically, the best pitchers' parks in their respective leagues. So, they've built around their pitching staffs. The Astrodome is a singles hitters' park, so Houston went for line-drive hitters and, wisely, ignored home runs. Oakland realized that its huge foul territory and grass infield were the reasons for low scoring, but that there was no reason home-run hitters couldn't prosper. So, like the Oakland champions of '72-74, the A's have selected power hitters with good walk totals.

Conversely, the common denominator of clubs that can't seem to get into serious contention, such as San Francisco, Cleveland, Texas and the Chicago Cubs, is an inability to settle on a coherent theory of team construction, and then have the conviction to stick with it. That also usually means hanging tough with the same general manager, manager, farm director and head of scouting long enough that the entire organization has a feeling of continuity from rookie league to major league.

"Even when you've got the nucleus of a good ball club, you have to be constantly tinkering with parts, parts that don't fit, parts that wear out. You have to tinker all the time," said Hank Peters, Orioles general manager. "But you should never overhaul. The teams who overhaul are the ones who are in trouble."

The Yankees, Peters said, are a perfect example. "They're a power team and then all of a sudden they say, 'Hey, let's become a speed club. We're going to win games with our team speed.' Then, in midstream, they decide New York fans don't like it, they're not winning games, and they want to change.

"That's when you start bouncing off walls. You require your players to play in a certain style and then you change your mind and the result is a mess."

The Orioles were able to let the recent trade deadline pass without scrambling for players because, "We set up the ball club the way we wanted it in October," Weaver said.

The Orioles' manager stuck with several players, most notably rookie third baseman Cal Ripken Jr., even when they were playing dismally, and thus was able to reverse a nine-game losing streak.

When you see franchises such as Cleveland, Texas and others that constantly seem to be moving fences in and out, or building new walls, it's a giveaway that the foolish club has, in its indecision, constructed a team that couldn't play even in its own park.

Of course, as every fan knows, several basic factors always have correlated closely with long-term team success. As Branch Rickey first proved long ago with the Cardinals and Dodgers, few things beat a fine farm system. Especially a farm system that specializes in teaching one thing well.

The Orioles, Mets and Dodgers have, traditionally, emphasized pitching and defense in the minors. The Reds, Pirates and Giants always have been noted for producing hitters, although the Giants usually trade theirs. In fact, the research of Bill James ("Baseball Abstract") indicates that the Giants actually produced more talent from 1958 to 1978 than any other club in basball, but traded it to the four winds.

Expensive farm systems are nice, but, as the Yankees are discovering, it isn't the quantity of pretty good minor leaguers that matters but the occasional genuine star--the Mike Schmidt or Eddie Murray--who changes a franchise's fortunes. Teams are built around a nucleus of stars; supporting players are a dime a dozen.

If you're strong in trumps, you can do a lot of finessing around the edges. Witness the who-are-these-guys "deep depth" of the '79-80 Orioles.

"It all boils down to what a player can do for me," Weaver said. "The one thing I'm very proud of is my baseball judgment, knowing a player's capabilities and what they can do for me at a certain time.

"Not everybody can be a Mickey Mantle. You have to be satisfied with one or two tools and make the most of them."

Take the case of John Lowenstein, Benny Ayala and Gary Roenicke, who have been three of the Orioles' most productive hitters this year.

But no one, save Earl Weaver, ever expected that would happen when the Orioles acquired those players. Lowenstein, now third on the team in home runs, was purchased on waivers for $25,000. Ayala was obtained in a minor-league trade after every other team in the majors passed him by. And Roenicke was the third player in a trade with Montreal.

"Those are three players who are helping our ball club out a lot, three players who we took a chance on when no other team was willing to," Weaver said.

Historically, trades have been a major factor in team building, especially the brave trade of a respected but limited veteran for a true prospect: Ernie Broglio for Lou Brock, Frank Duffy for George Foster. However, in this era of agents, no-trade clauses, right of veto and the like, trades are so tangled that their importance has diminished.

Nevertheless, a fellow who knows what he wants still can pull it off. When Herzog inherited the Cardinals, he wanted more speed, a veteran catcher he trusted and more relief pitching. So, he managed to trade for Lonnie Smith, Darrell Porter and Bruce Sutter.

Finally, it is indisputable that being rich always has helped, but it helps more than ever now. Gobbling up quality free agents is an obvious route to improvement. Nevertheless, the evidence of the past six years still seems to indicate that, as often as not, some big spenders--in California, San Diego, San Francisco, Texas and Cleveland--simply lack that basic idea of what they're trying to create. Even some winning teams, like the Dodgers and, so far this year, the Braves, have done themselves little or no good with their free-agent spending.

One of baseball's most basic appeals is the degree to which it rewards the creative, conceptualizing work of one guiding brain, or, at any rate, a tradition of ingrained organizational intelligence.

The clubs that best illustrate this stability and wisdom in baseball judgment have been the Dodgers, Orioles, Yankees and Reds.

And, in the past 25 years, the four organizations with winning percentages above .550 have been the Orioles (.569), Yankees (.560), Reds (.557) and Dodgers (.553). In that time, those four clubs have made 29 World Series visits while all the other clubs in the sport have been to the classic only 21 times.

All four have an organizational "book" on how every technique and fundamental of the sport should be executed; this links the lowest busher with the star.

All, except the Steinbrenner Yankees, show great patience. They refuse to panic in those occasional years of failure. All bring prospects along slowly, working them into the lineup in can't-lose situations. And, at the right time, all give a solid, long-term commitment to those young players--be they Steve Sax, Cal Ripken Jr. or Paul Householder.

In fact, many of the Yankees' current problems may stem from the degree to which the owner has stopped listening to his baseball men and started consulting himself. The hasty, emotional decision has, for a century, been the enemy of success in baseball.

Countless factors go into a major league team's success. However, the most important may well be the person who nurtures the central idea of what the final team on the field should look like.

If he is Oakland's Billy Martin, then he decides who his best four or five pitchers are, either starters or relievers, then rides them until they drop. (Then leaves town.)

If he's Milwaukee General Manager Harry Dalton, then he looks for power and a glamor lineup, even if he must patch his pitching as he goes.

If he's Mets Manager George Bamberger, then he looks for four starters whose confidence he can build and who can learn all the wiles that he can teach.

And so on.

In baseball, any one of many proven approaches to winning will work. But only if the people running the ship have the courage of their convictions.

And that's even rarer than a good idea.