Are you seriously asking this unironically?
When he arrived City had:
Hart, Otamendi, Kompany, Kolarov, Clichy, Zabaleta, Sagna, Fernandinho, Fernando, Delph, Yaya Touré, De Bruyne, Silva, Nasri, Sterling, Aguero, Bony
On that summer he bought:
Bravo, Stones, Gundogan, Nolito, Sané
And on winter:
Jesus
The players you mentioned left City... because City had even better options already in the squad for almost all those players.
Yaya and Clichy obviously didn't get a better club after City because... they were old already.
Otamendi / Kompany / Kolarov / Fernandinho / Yaya Touré / Silva / Sterling / Aguero
This is an almost complete team of players that have been some of the best in the Premier League in the previous seasons.
City not only had these but also a ton of good but not starter material players, several like many I mentioned above.
He not only inherited this already very high quality spine but kept adding more and more players every transfer window and could ditch 40 M€ players in the next window if he wanted to because the club kept buying whatever he wanted.