IT was an unforgiving, overcast day in late June 1950 in Belo Horizonte, Brazil.

Soccer's World Cup was under way, and mighty England, with stars such as Bert Williams in goal, Alf Ramsey, Billy Wright and Tom Finney, was squaring off against a collection of upstarts from the United States.

The U.S. team was composed of a handful of players from St. Louis, some East Coast ethnics and three expatriates - no great names. No one expected the Americans to offer the English much resistance.

When the final whistle blew, however, one of the major upsets in sports history had taken place.

A header by Haitian-born Larry Gaetjens in the 37th minute - many called it a lucky goal - secured a 1-0 victory for the Yanks against the eleven from the Mother Country of football (as the rest of the world calls the game).

But the U.S. national team went on to lose 11 of the next 13 full international matches played in the 1950s and the reconstruction of international soccer for the United States has been a long, uphill grind ever since.

"They're not going anywhere," said Paul Gardner, referring to the U.S. national teams. Gardner is a British-born New York-based soccer expert who handles the color commentary for ABC-TV's national telecasts of North American Soccer League games.

"In simplistic terms, we don't have the players because there is something wrong with the way we're bringing players up."

Gardner's comments tend to be at the extreme end of the spectrum, but the thought is echoed by many insiders in the U.S. soccer scene. Despite the growth of the world's most popular team sport in this country, the United States has a long way to go before it can compete on equal terms against the world's elite.

The phenomenal rise of youth soccer in the United States in the last decade, coupled with the emergence of a viable professional league in the NASL, has led to unbounded optimism among soccer people from coast to coast that the Americans soon could become a world power in soccer.

The conventional wisdom among the optimists, is: "Give us five to 10 years, and we'll be right up there with Argentina, the Netherlands, Brazil and West Germany. We'll be competitive."

Yet a more realistic view is that while U.S. soccer teams are making progress, the progress is much slower than many impatient American soccer boosters would care to admit. Furthermore, many obstacles appear to be blocking the path toward parity with the giants of international soccer.

Three recent international matches have forced the Americans to own up to their current modest role:

A May 2 exhibition game at Giants' Stadium in East Rutherford, N.J., between France and the United States "A" team, that is, an all-star team composed of the best available American players, professional or amateur. The U.S. team, hopelessly outclassed, lost, 6-0.

The U.S. amateur team's May 23 loss in Leon, Mexico, to Mexico, 4-0.

The June 3 return against Mexico at Giants Stadium, also won by Mexico, 2-0, eliminating the U.S. team from the 1980 Olympics.

The encounter with France, against a team that probably ranks among the world's top 10 national teams, was a chance to show the strides American soccer has made. Yet, despite being on their onw (artificial) turf, the Americans were outmanned all over the field.

"We're not as far along as the euphoria [over some U.S. successes] would have you believe, nor are we as bad as the 6-0 against France would indicate, said Clive Toye, president of the Chicago Sting of the NASL and a longtime observer of the U.S. soccer scene at all levels.

And, on balance, it should be noted that the U.S. "A" team had a good tour of Europe late last summer, although even its best results were far from world-class performances.

The Americans beat a good French professional club, Marseille, 1-0, fought Iceland's national team to a scoreless draw and managed a 1-1 tie against the Antwerp club of Belgium.

Switzerland, which is considerably stronger than Iceland, beat the U.S. team, 2-0; Scotland's under-23 team won, 2-1; Portugal won, 1-0, and in the only rout, Borussia Dortmund of West Germany's tough Federal League beat the Yanks, 4-0. Still, none of the six opponents could be considered among the current international powerhouses of soccer.

If all the world's teams were rated on a scale from one to five, U.S. national teams Coach Walt Chyzowych said in an interview, the tour showed "we can play with the fours and hold our own."

Such optimistic talk was getting prevalent among the leaders of the United States Soccer Federation, the ruling body of soccer in this country, until the French came.

"Well, I suppose this'll send us back to the drawing board," one USSF official was heard muttering in the press box after the 6-0 debacle.

So what happened against France and against Mexico? Were those matches aberrations or part of a general pattern? After noting that the French won nearly every direct duel on the field, Chyzowych conceded to reporters in the U.S. team's locker room that, "Our players are not prepared to play mentally faster" than they did against an opponent of France's caliber.

"We lack technical speed," he said. "I don't mean our guys are slow, it's just that when it comes to executing the basic skills, the French were able to do everything a split second faster and it takes our guys a split second longer to react."

Critics of the American teams say this is a natural outgrowth of what lies at the heart of the problem: the Americans simply do not have the skills to compete with the best from abroad - and they appear unlikely to learn them.

"It's the mentality," said ABC's Gardner. "I don't think there's anything wrong with the athletic qualities of the players, whether you're talking about strength, speed, muscularity or skeletal aspects.

"The American kids are led to understand early on that the true nature of soccer is hustle, aggression, toughness, kick and run, that's what they're praised for doing. But they never learn the skills."

Toye agreed. "There's too little attention paid to ball skills [at all levels]," he said. "They don't learn finesse."

Most youth coaches, for instance, drill their players on tactics and conditioning or will have players taking penalty kicks at the goalie, he said, and "the kids are lucky if they're touching the ball every 10 minutes."

"It's not Walt Chyzowych's fault, is it?" Gardner said. "If he's calling players into the national team, he's got to think they're mature.... He can motivate them, teach them tactics, but he can't teach them how to play soccer when they're 22, 23 or so.

"If they can't play the game by then, well they'll never learn it, really."

Another problem for the U.S. national team is that there are too few American players getting regular playing time for professional teams, which limits the pool of players available to Chyzowch.

"The fact that our players do not play 10 months a year really hurts us," Chyzowych said. "They do not play enough games. A European player is in 50 to 60 matches a year while our player is in 20 to 30."

Furthermore, because the needs of the league's teams do not always coincide with those of the national teams, Chyzowych has found he cannot always get all the players he feels he needs for a particular game. CAPTION: Picture, Perry Van Der Beck of St. Louis, who plays for Tampa Bay Rowdies, goes high to hit header for U.S. national team in recent qualifying match for Pan Am Games against Canada, a 0-0 tie.