A spectator holds up a poster to protest against corruption before the Brazil-Italy Confederations Cup match Saturday. Agence France-Presse/Getty Images

Some 10 minutes into Saturday's Confederations Cup match between Mexico and Japan, a shirtless young man left his seat at Belo Horizonte's Mineirao Stadium and approached the stairway separating his section from the press box.

He carefully unfolded a large sheet of paper and held it a few inches from the noses of the closest journalists while shouting slogans. It read: "More education. More transportation. More health care. Less FIFA stadiums."

The assembled media duly looked away from the match, reached for the smartphones and tweeted away. Security gave him a good five minutes to make his case before gently escorting him not to a police van, but back to his seat.

As an episode, it encapsulated the nature of much of the protests that have engulfed Brazil over the past week. They are largely middle-class. (Indigent people don't buy tickets in the nicer parts of Confederations Cup stadiums.) They are peaceful. And, especially in front of a phalanx of journalists, they are met with gentle policing. (Elsewhere, at times, it has been a different issue.)

The handmade sign summed up just why well over a million Brazilians have taken to the streets. The economy—which was growing rapidly in October 2007, when the country secured the right to host the 2014 World Cup, and booming two years later, when Rio de Janeiro was awarded the 2016 Olympics—has now slowed down, while the bill for the massive spending on infrastructure and venues continues rise.

Hosting major events such as these—let alone two years apart—is an exercise in economic theory. Boosters conjure up studies aimed at proving the long-term net benefit to the economy of what amounts to a giant stimulus package: $13.3 billion in the case of the World Cup. Sometimes they try to put a value on intangibles like national pride.

Critics say there is an opportunity cost and that the cash could be better spent elsewhere. And they also point out that if a new subway or highway is worth building, it's worth building regardless of whether it's going to carry visiting fans for a month of soccer games or Olympic events.

When things are going well, folks buy into the former argument. When they aren't, the latter creed has the upper hand.

The twist here though seems to be the incorrect—and, frankly, condescending—assumption that because Brazil is a soccer-mad country, once the tournament starts and the famous green-and-gold "Selecao" start to win, nobody will care about the opportunity cost of it all.

FIFA president Sepp Blatter said as much in an interview on Brazilian television: "When the ball starts to roll, people will understand!"

He added that, while he understood that people were unhappy, they "should not use football to make their demands heard." To complete the gaffe, he reminded them that nobody forced Brazil to bid for the World Cup. Sensitivity and empathy, evidently, are not his strongest qualities.

For its part, Brazil's soccer community has sided squarely with the demonstrators. Support has come from a number of Brazilian players, current and former. Hulk, a forward on the national team, said in a news conference: "I see these demonstrators and I know they are right."

Former international Juninho Pernambucano went so far as to suggest that the national team show solidarity with the protests by turning their backs to the flag during the traditional playing of the Brazilian anthem before games.

On the pitch, all of this has likely benefited Brazil. Its coach, Luiz Felipe Scolari—who managed the team in 2002, when Brazil last won the World Cup—had endured a rocky time in the buildup to the Confederations Cup, winning just three of eight friendly matches. With a FIFA ranking that has slipped to 22nd (partly a quirk of the mathematical formula used to rank the sides, but not an entirely unfair reflection of the relative strength of the side) and a team that appears less talented than previous versions, he needed a strong showing in the Confederations Cup, the traditional World Cup warm-up.

Brazil sailed through the group stage, winning all three games, including a 4-2 victory over Italy on Saturday. The play has been mostly efficient and only occasionally breathtaking—usually when Neymar, the young Barcelona-bound starlet, has been on the ball—but the notoriously demanding Brazilian public, perhaps distracted by what is going on in the streets, doesn't seem to mind.

Which, when you think about it, suggests the country has come full-circle. In the past, soccer—particularly success in the World Cup—was the distraction that kept some Brazilians from worrying too much about the brutal military dictatorship that ruled the country from 1964 to 1985. To paraphrase Karl Marx, soccer was the "opiate of the people" that helped to keep the masses at bay.

Today, it's the other way around. Love for the Selecao continues unabated but, at least for the past 10 days or so, it is a relationship consumed on the margins. The real focus is the economic and social change the protesters are demanding.