i cant speak for the chabad community in la but for the other communty, ie those who went to toras emes, i can say that there is a lot less kids per capita going off the derech than there is in ny. (cant either speak for yavne or hillel)
which can be attributed to 2 reasons imo:
1. in la, there isnt the "box" that you must fit into. you can find your place whoever you are. in ny its not that way
2. in la, kids are somewhat exposed to the non jewish culture. unlike a kid out of sheltered boro park, that after seeing an inappropriate billboard for the first time, ditches his yarmulka