It really depends on the professor you're working with. For my case exceptionally, I didn't have any connection to the research group that I applied. However, they hire from a closed circuit. Mostly french, Russians, and prince and possibly princesses from Saudi Arabia. How is it possible that a french guy and her wife are both eligible to get a job in the same group in the same department, especially when they are not witty at all. So.... Stanford collects some talents , it has to, to run the business, the rest of it is wealth and power!