Why Your Top Performers Leave — And What Their Nervous System Was Telling You
By BrioMon Team
A resignation from a strong performer almost always lands as a surprise to the organisation and almost never as a surprise to the person who submitted it. The gap between those two reactions is where the real cost — and the real signal that got missed — actually lives.
The cost is well-documented, and larger than most budgets account for
Economists Heather Boushey and Sarah Jane Glynn, in a widely-cited analysis for the Center for American Progress, reviewed a large body of research on employee replacement costs and found that the cost of replacing an employee typically runs from around 16% of annual salary for lower-wage, high-turnover roles up to more than 200% of annual salary for highly specialized, senior positions — driven by recruitment, onboarding, lost productivity during ramp-up, and the knowledge that leaves with the departing employee (Boushey & Glynn, 2012). For an organisation's strongest performers, the cost sits reliably at the higher end of that range, since their roles tend to carry the most specialized knowledge and the longest ramp-up time to replace.
Why the decision to leave is rarely sudden
The actual decision to leave a role is very rarely made in the moment a resignation is submitted. It's typically the endpoint of a much longer process — sustained strain, a mismatch between effort and reward, or a slow accumulation of unaddressed friction that eventually crosses a threshold. By the time the resignation letter arrives, the organisation is usually seeing the outcome of a process that's been running, quietly, for months.
What gets missed along the way
Because the underlying process is gradual, the earlier signals rarely look dramatic enough to register as a retention risk. A previously highly engaged performer becoming slightly more withdrawn, slightly less willing to go beyond the baseline, slightly quicker to disengage from a project that would once have generated enthusiasm — these are subtle shifts, easy to attribute to a busy season or a personal off-week rather than to a genuine, accumulating depletion of the capacity that engagement itself depends on.
Why top performers are often the last to show visible signs, and the first to actually leave
Strong performers frequently have well-developed coping strategies and a track record of pushing through difficulty, which means their outward performance can remain high for longer even as their internal capacity is quietly eroding. That combination is genuinely dangerous from a retention standpoint: the person most capable of masking depletion behind continued high output is often also the person with the most external options once they finally decide they've had enough.
What this means for how retention risk should actually be tracked
If the decision to leave is a slow accumulation rather than a sudden event, then retention efforts focused only on counteroffers at the point of resignation are addressing the problem at the one moment it's already too late to meaningfully change. The more effective window is much earlier — tracking the subtler signals of accumulating depletion in high performers specifically, since their capacity to mask strain behind continued output means the usual visible warning signs arrive later for them than for almost anyone else on the team.
See how BrioMon helps you catch the signals before the resignation letter — Book a Demo.