The previous coaches delivered EPL trophy, FA cup, and the League cup but still got their arse kicked out because the owners wanted someone to bring them Champions league to put their name on the elite list.
Mancini and Pellegrini both won one epl title each and a league cup each, pep has done more than that, in a more resounding, dominating and domineering fashion, pep is not just winning leagues on goal difference like Mancini did, he is conquering England, breaking records left, right and center, that's what's different, pep is going for his third EPL title, he has won an unprecedented domestic treble and hasn't let go off the carabao cup since he came to City, pep is making a difference. Of course, the CL is so important for City and I'm sure pep is going to deliver that, and even if he doesn't, he still remains a huge success at the Etihad.
Man City defense is still weak, what's keeping mancity is the compactness of their midfield, it's very difficult to penetrate, once you are able to expose the midfield then winning them is easy.
Are you kidding me, City by far have the best defense in England this season, Pep's team is always compact, and chase down the opposition immediately they lose possession, but even with that, if your defense is weak, you'll concede cheap goals, and that's been City's undoing in the past; are you following the progress of Dias and the rejuvenated Stones, they are somewhat impregnable, IIRC, City have conceded only 15 goals in the league, and very few in the UCL group stages, even Laporte is a rock anytime he plays, if you're closely following this season, you'd see a massive improvement in City's defense and that'll be the deciding factor for them to win more than just domestic trophies this season.