That's the problem. Ex-Chelsea players are playing well elsewhere. Other clubs took advantage of Chelsea system: players in and out in no time.
After observing Chelsea for some seasons, I realized that Chelsea wants to fix things quickly. People are not patient enough to wait for a stability. New players come. If they don't blend in immediately, we say that they are suck. Everything needs time.
Maybe, Chelsea fans enjoy the rich atitute too much. Since other teams don't have that kind of money, they are more patient with players and plaeyrs flourish in their system. That's life.