Generally good managers know when the best are leaving. There are other challenges at work. For instance - if a team is still hitting it's numbers, the manage

Generally good managers know when the best are leaving. There are other challenges at work. For instance - if a team is still hitting it's numbers, the manager may not want to make a change. Or there could be no other leadership alternatives. Or they don't want to set the precedent of team mutiny. Hard to know without knowing the details of the situation, but sometimes there is more going on than meets the eye. And yes - this should be trivial to measure. Hiring a good employee costs X. Of those, 1/Y is a great one. The cost of losing a great one is XY. XY is usually significantly higher than a year's salary. For the same reason, I also think managers should be rewarded for creating great employees and giving them to the broader organization.