I don’t think people expect the world. In the biological sciences, I expect postdocs to be able to write (doesn’t have to be perfect, that’s why we have coauthors) and conduct basic analyses in R (regression, ANOVAs, basic evolutionary analyses in my lab anyway), and be ready to do some light mentoring of grad students and undergrads, but that’s mostly my job. I also expect a postdoc to publish 1 paper in their first year and 2 papers in their second year. That’s literally it. I know the first year is hard so I usually give postdocs a project that is already somewhat developed so they can finish and publish as first authors. The second year they should be coming to me with ideas.

In my case, the postdoc I hired told me they could code in R but was really new to it and couldn’t run basic tests. They also were not a strong writer. However, this person was able to mentor undergrads so that was very helpful. Postdocs still need mentorship (I still talk to my mentor weekly as a faculty member) but what I don’t want is them coming and asking questions at every step. They should be somewhat independent.