You don’t know anything. It’s something you’ll have to accept.
You don’t know what your team is thinking. What they say about you or each other behind your back. What is happening in their personal lives that could affect work. Who is interviewing for another gig.
We live in a world of unknowns; a world of massively imperfect information.
As a result, you need to learn to trust your gut.
When you lose sleep over an employee’s performance, they’re probably not the right person for the job. When someone is conspicuously absent from work, they’re probably interviewing. And…the list goes on.
This doesn’t mean, however, that you should make hasty decisions. But if your gut is even moderately fine tuned it will become one of the best indicators of people dynamics you’ll have.