A bad Head of Sales hire doesn't show up right away. That's exactly what makes it costly: by the time it becomes visible, the damage is already done to the team, the pipeline, and the quarter's targets.
The direct cost: more than a salary
The most commonly cited estimate (US and French HR studies converge here) puts the direct cost of a failed hire at 30% to 50% of the role's gross annual salary: initial hiring time, onboarding, any severance, then an entire new hiring cycle to restart from scratch.
For a Head of Sales on a €90-120k base, that's easily €35-60k in direct cost, before even counting the impact on the team.
The hidden cost: the team and the pipeline
This is where the real damage happens. A Head of Sales who can't coach, structure a process, or make the forecast reliable has a direct effect on their team:
Cascading turnover: the best reps, poorly managed, leave first, they're the ones with the most options elsewhere.
A poorly qualified pipeline: an optimistic but unreliable forecast eventually blows up at quarter-end, hurting credibility with leadership.
Delayed trajectory: the time lost fixing the organization is often counted in quarters, not weeks.
Why it takes so long to notice
A bad Head of Sales isn't necessarily incompetent in an interview: they can sell their own profile convincingly without ever having actually carried a quota or managed a team that performs. It's often only at 6 or 12 months, once turnover and missed forecasts pile up, that the problem becomes visible, and by then, the cost is already largely locked in.
How to reduce this risk
Check the actual track record, not the pitch: have they personally carried a sales quota before managing? Coaching credibility is earned in the field, not on a resume.
A structured interview process with several stakeholders and an evidence-based evaluation grid, not gut feeling.
A contractual replacement guarantee from the firm or RPO that led the hire, to limit exposure if it still goes wrong.