He was never in a situation where he NEEDED to adapt until he came to City, so you're doing a guesswork, too. And the first time in his career he didn't have an absolutely best squad in the league at his disposal, even after spending a small fortune, he finished 3rd. That's not a disaster, but it's not a good sign, either. So he goes out and spends yet more piles of money on top of it and suddenly he's a genius again.
Guardiola is absolutely a top manager and his teams play some great football but I don't think he'd have won the CL with Porto in 2004, Liverpool in 2005, Inter in 2010, or Chelsea in 2012. He wouldn't know how.