What can a PI do about a low-performing postdoc? This is a hypothetical question inspired by a flip side of the situation described here.

Consider a PI on tenure-track position, facing tenure / promotion panel in a few years. The PI has just got their first significant research grant, allowing to recruit one postdoc (research fellow) and maybe buying out a few hours per week of PI's time to administer and manage the grant.

After careful selection and recruitment process, following the regulations of the University HR Department, a shortlist was composed, the interview was held, the best candidates were identified and finally one of them accepted the offer and arrived to start the post. Suppose the project and the funding is for one year only.

Following the usual induction process, a program of research has been agreed and weekly meetings has been set to monitor the progress. A few weeks later, the PI is worried that the progress is slower than anticipated. The majority of time is spent by the postdoc on reading the  literature, discussing the problem with other PhD students in the group, formulating strategic suggestions on how to solve the problem and possibly also problems of other students in the group. However, when it comes to writing publications (and scientific code when appropriate), the progress is insufficient.

Suppose that the PI has tried to focus the postdoc on their area of responsibility by making verbal remarks, but it did not improve the situation and only made the relations a bit tenser. The PI feels that the postdoc is under-performing, but the postdoc denies such discussions and in discussion with other students describes them as non-constructive and abusive.

The question: Assuming the restrictions and processes of your current University (or other places your are familiar with), what would you do as the PI in this situation? 

I assume that the short-term goals of the PI in this situation are to produce enough high-quality publications to successfully complete their grant, secure the following grants and increase the chances of successful tenure. However, if there are also long-term goals which are more important and should influence the chosen strategy instead, please describe them. I also assume that 3-4 hours per week is just about how much time the PI has to manage this grant, and the rest of the time is spent on teaching, working with PhD students, etc, so the strategies requiring let's say 2 hours of PI's time per day are not very realistic. This is based on the typical breakdown of time for EPSRC First Grant scheme in the UK &mdash; please feel free to point out if it's not applicable in other places.
This really depends a lot on the contract situation. In some countries, such as Germany, there is a “probationary period” of several months wherein either side can choose unilaterally to end the contract. This lowers the risk from a bad hire. Saddled with a hire gone wrong, I’d try to get what output I could from the postdoc during the period and start a new hiring process right away (or see if anyone from the previous search was still available!).

In countries like the US where contracts may not include probationary periods, you have to try to figure out how to best help the postdoc out, since you’re stuck for a potentially much longer period. If it’s some sort of missing knowledge you figure out how to provide that. If it’s some other issue, you try to work around it or solve that problem. Without a more specific example, it’s hard to draw up a good “plan of action.”