system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5 When a company headhunts an employee from another company, how do they know how well that person is performing and how much of their companies success can be attributed to them?
gpt
They often don't because they can't ask that company directly. That's highly indiscrete and would really tick off the hiree, unless he or she had made it known that they were intending on leaving and gave their permission for the contact.

Generally recruiters rely on other ways of measuring that person. These include assessing the person's resume and educational history and industry certifications, results from testing and interviews, checking references from previous companies that the target might have worked for, contacts with prior knowledge of that individual that have either worked directly for them or were their customer or business partner, and online searches on sites like LinkedIn.