Every organisation eventually meets the problem: the salesperson with the best numbers and a trail of burned-out support staff, the engineer who's brilliant and impossible, the operations manager who hits every target by quietly torching every relationship. Leadership tolerates it, because the results are real. But the tolerance is a decision, and it's more expensive than the results are worth — because it redefines performance for everyone watching.
Two dimensions, one definition
The correction is definitional, not moral. Performance is the achievement of desired strategic goals — which makes clarity about goals the fundamental premise — and it has two dimensions that don't average out: what got delivered, and how. High results delivered with poor behaviour is poor performance. Pleasant behaviour that doesn't deliver results is also poor performance. Neither dimension can buy back the other, because each one destroys something different when it's missing. Missing results destroy this year's outcome. Corrosive behaviour destroys the conditions other people's results depend on — trust, information flow, the willingness to raise problems early — and that damage compounds across every team the person touches.
High results with poor behavioural delivery is poor performance. Nice people who don't deliver results is also poor performance.
What tolerance teaches
The deeper cost of carrying a high-results/poor-behaviour performer is educational. Everyone in the organisation runs the same quiet calculation: what actually gets rewarded here? If the answer is "numbers, however achieved", the stated values become decoration, and the organisation starts selecting for the behaviour it claims to reject. The most capable people — who have options — tend to leave first, which means the visible results the exception generates are being paid for with invisible attrition somewhere else on the ledger.
There's a mirror-image failure that gets less attention: the well-liked underperformer, protected because the behaviour is warm and the relationships are good. Carrying them teaches a different lesson — that delivery is optional if you're pleasant — which is just as corrosive to the people quietly carrying the shortfall.
Making both dimensions real
Definitions only bite when they show up in consequences. That means behavioural expectations described concretely enough to assess — not "be collaborative" but the observable forms: shares information before being asked, raises conflict directly with the person rather than around them, treats support staff as colleagues. It means both dimensions carrying weight in reviews, promotion and pay, so the two-dimensional definition survives contact with the annual cycle. And it means the leader having the hard conversation with the brilliant exception early — adult to adult, specific about the behaviour, honest about the stakes — rather than banking the results and hoping. Most turn out to be coachable once the trade they've been running is named. The ones who aren't were never high performers. They were high producers being subsidised by everyone around them, and the definition exists precisely so that difference is visible.