The Catalan has failed to win the Champions League with either Bayern or City since leaving Barca in 2012.
"With Pep Guardiola I have the feeling that he always wants to do something special in big games," the ex-Bayern and Germany defender told Sport Bild. "Barcelona had a DNA, a system he pulled through. Pep was successful there. With Bayern and City, he tried it over and over again with changes and failed again and again.
"He always wanted to show that he could do even better. I would like to tell him: Pep, you are a giant trainer – but please keep your system!
"I would describe it as egocentric. Yes, that's a harsh word, but it is due to what he did. At Bayern, Robert Lewandowski even had to play left wing once. That did not work out at all."