Look for the people that everyone mocks
Pay very close attention to them. Nothing marks a trouble spot in quite the same way. Either they’re being picked on and something needs to be done or they are the first people you should be helping to pursue new opportunities. Very far away. Either way you need to know.
Leaving incompetent people in place destroys morale for the good staff and encourages them to look elsewhere. When there’s a bad apple or two lowering the teams value, and the quality of their output, pure professional pride only gets you so far. At some point you need to have a culture that rewards effort and punishes wastes of space.