Ronald Koeman has accused Barcelona of living in the past as the Dutch coach took aim at his former club.
Koeman was dismissed in October and was replaced by club legend Xavi in the dugout.
And Koeman, who is set to take over the Netherlands national team for Louis van Gaal after the World Cup, says Barca is still living in the past and have not grown from a reliance on tiki-taka possession-based football.
What did Koeman say about Barca?
"I am in favor of dominating the game," he told Esport3. "If you play with three central defenders and five defenders, you cannot say that it is a defensive system.
"With this system for three or four months we played the best games in recent years. The clearest example was the final against Athletic.
"Barca lives in the past, from 4-3-3, from 'tiki-taka'. Football has changed. Now it's faster, more physical. You can't live in the past."
Koeman weighs in on Lewandowski links
The Dutch manager also weighed in on the club's links to Robert Lewandowski, who has expressed his desire to leave Bayern Munich this summer.
Koeman is a fan of the Poland star, but says he has doubts about paying a big fee to secure Lewandowski's services.
"Lewandowski is a great player, a regular goalscorer, but he is of a certain age," he said. "35 years old? I have my doubts about paying 50 or 60 million for a player, in addition to his salary.
"Maybe he has two years left. I would have many doubts about signing him or not sign him."