I agree and West Ham are more prone to surprise defeats then any of the other sides albeit they are probably the best of the four in H2H vs City/LFC/Chelsea.
Probably because we discovered it is damn hard to compete on 4 fronts without almost unlimited resources.
Also the domestic cups are taken way more seriously by the wealthier clubs than before - almost used as leverage if they don't win either the league or CL.
City have won 6 of the last 8 League Cups and the other two went to Chelsea and Utd. Clearly down to Pep's genius. That or having a million players and almost unlimited money. One or the other.