Jim Collins' talked about a bus analogy, which has direct implications for staffing. These implications include:

all of the these

coach and develop the right people to reach the top deck of your bus $($promotion$).$

get the right people on your bus by stopping at the right place $($recruit wisely$)$

stop to let certain people off your bus $($those who won't or can't perform$).$

get people in the right seat $($doing the right job$).$