Three-time FIFA World Player of the Year Ronaldo believes that last November's sacking of national coach Mano Menezes has set Brazil back in its preparations for the next year's World Cup.
Menezes was dismissed in November last year, just days after leading Brazil to the Superclassic of the Americas trophy with a dramatic penalty shootout victory over Argentina in Buenos Aires, Xinha reports.
He was replaced in December by 64-year-old Luiz Felipe Scolari, under whom Ronaldo played in Brazil's 2002 World Cup-winning team in Japan and South Korea.
"I think the change was too soon," said Ronaldo, who now runs a sports marketing agency and is an ambassador for Brazil World Cup organising committee.
"I feel comfortable saying this because I have nothing to do with the CBF. Mano was starting to get results and the team was playing better."
"Despite the fact there is still time before the World Cup, Brazilian fans want the team to be strong now. They want Brazil to be winning and playing well. The change of coach set the team back."
Brazil is yet to win since Scolari's re-appointment, losing 2-1 to England in February followed by 2-2 and 1-1 draws against Italy and Russia last month.
While he did not directly criticise Scolari, Ronaldo said he rated Corinthians manager Tite and Santos boss Muricy Ramalho as Brazil's best current coaches.
"I know the Felipe of 2002. But we are now in 2013. For that reason it's difficult to say how he will do now," Ronaldo said. "My memories are of a fun, happy guy who is a great leader of men. He will win the players over quickly and form the Scolari family number two. I hope he can repeat the success of 2002."
Ronaldo said Brazil, currently at an all-time low 18th in FIFA's world rankings, are still far from defining their World Cup team.
He cited Santos striker Neymar, Chelsea midfielder Oscar and Paris Saint-German defender Thiago Silva as the only players close to securing a berth in the squad.
"No player is ever 100 percent sure of playing for Brazil, even in the days of Romario and Bebeto," Ronaldo said. "There is always a shadow. But there are players that have big chances of being selected, which is different."
"I don't see any alternative other than to persevere with the players that Mano used and that Felipe has now assumed. It's the coach's job to motivate the players to play for their lives every game."