Pep is a great coach, surely one of the best in modern times but the reason people call him overrated is because of how his fans just think he is some messiah of football. Truth is without the crazy money he has spent which by the way he is number 1 on the amount spent for a manager since 2008, he would not have achieved this much which begs a question whether he is really a genius. He has been badly found out this season and the only way he can bounce back is by spending another 200m. Not every manager get that privilege.Like i said, other coaches might have won as much or maybe more, but non of them would have made the teams he coached play and win the way he does and that is one of the major reasons why almost every team that can afford him will still want him if he leaves City tomorrow. And that reason i feel is really being overlooked by a lot of people that don't like him as a coach or feel he's overrated.
Messi was already the undisputed best player in the world when he arrived? That Barcelona team (that has since then been called the best team ever by a lot of people because of how he made them play) was already great before Pep arrived? That's basically re-writting history.
Pellegrini and Mancini had resources at City too, but you never hear their names come up in the discussion of the best coaches ever while Pep's name does and there's a reason for that.
Having those players is one thing, using them the way he's done (especially the Silva-Debryune duo) is another thing and that's what IMO you're underrating. Besides, Kompany didn't feature much under Pep except for the 2nd half of last season.