Most “not a fit” decisions are a confession the manager has not made yet. The person under review has a real gap. The manager has not named it. Naming it would require sitting with the discomfort of having hired wrong, or coached wrong, or measured wrong. “Fit” is the word that lets a manager skip that step.
The pattern shows up the same way every time. A new hire is brilliant on craft and slow on context, or sharp on context and brittle in critique. Three months in, the manager senses something is off. They cannot articulate it cleanly, so the team starts to feel it too. Two more months and the language drifts toward fit. The fit conversation is gentler than the gap conversation. It does not require the manager to admit they were unable to grow the person they hired.
The honest version is a list. Three behaviors that are blocking the work. Two of them are coachable. One might not be. Show the list to the person. Give them eight weeks. Either the behaviors move or they do not, and at the end you have a decision both sides can describe in plain language. Nobody is fired for fit. Somebody is let go because a named behavior did not change after a named intervention.
Counter-view: there are genuine value mismatches that no coaching closes. A designer who believes the user’s stated preference is the final word will struggle in a research-driven team that treats stated preference as one signal among five. That is not a discomfort, that is an alignment gap, and it shows up in artifacts within a week. The fix is the same: name the gap, give the conversation, give the time, then decide.
The manager who fires for fit is protecting their own narrative more than the team. The manager who fires for a named, measured, coached gap is doing the actual job.
Takeaway: if you cannot describe what the person needs to do differently in one sentence, you are not ready to let them go.