The Dutchman, who coached Dortmund from 2004 until 2006, feels the Bavarians' Champions League semifinal dismantling of Barcelona saw the team supplant the Catalan giant as the continent's finest side.
"Bayern Munich are the new benchmark in European football in my opinion," he told Voetbal International. "It's a shame, but I don't think that we will see Barcelona's style of play again. They were able to hide their vulnerability over the years, until they were exposed when their form dropped a bit.
"Bayern's players are at an age where the current team can go on for two or three more seasons. And what's really impressive is that they have plenty of cash in the bank. They could easily spend 100 million euros on new players if they wanted."
The former BVB manager went on to say that he believes the team he once managed will struggle to deal with Bayern in Saturday's final.
"I really believed that Dortmund could win the final and that it would be 50-50," he said. "But I'm having second thoughts after last weekend. I was in Dortmund for the game against Hoffenheim and they disappointed me. They looked complacent and their defense gave away too much space.
"Bayern have length, speed, physical power, creativity and score a lot. They're like a machine that's able to use several different styles of play."