Those NY guys that ended up with the NJ Family were regarded by the NY Families as pretty much unusable. They didn´t want them. But they still vouched for them.
When "tranfered" to the NJ Family, they were still only "connected guys" and it wasn´t like they were being made overnight. In some cases, it took years before they got made and during that time they were carefully evaluated by the NJ bosses.

One funny thing about it is that the NY Families put an end to NJs recruitment of NY guys and withdraw their consent of it.
This was in the 80s (I think) when the talent pool (even in NY) was getting slimmer. However, this didn´t stop the NY Families from recruiting guys from New Jersey!