Cos he will never ever find anything like City anywhere else . No internal politics, no president of a club sticking the knife in , no backroom skulduggery, he is part of the management team not just the hired coach that can be used as a scapegoat . I would guess that he thought that Barca would be where he cemented his legacy, but look at how politics has wrecked that club over the years, what he has at City is almost unique in the football world , an owner and a management team that all pull in the same direction at the same time, why would you let a lesser manager inherit that when you are at the top of your game ?