It depends on their skillset. We base expectations (and compensation) on how much immediate impact we expect. The non-negotiables are that the person has to operate by our principles and values and therefore that they are earnest and excited to do their best.
So when an intern comes in we expect to see some exciting work, maybe 10% of which we can actually use. When a senior person comes in we expect to see 100% of their work be at a high level (or for them to try again until it is).
The other aspect of what new people add is diversity. Diversity of Everything is one of our values. We like to have an open community where people feel safe sharing their stories and experiences. We learn so much from each other. We have people of many different faiths, career backgrounds, demographics, skills, and attitudes. 4 billion people have internet access so the more understanding we have of people and their varied qualities and outlooks the better we can serve the audiences of our sites. So I am always eager to understand the new perspectives that each person brings to the group.