This depends on the organizational structure and politics of your company more than almost any other factors. If you are a small startup and top level executiv

This depends on the organizational structure and politics of your company more than almost any other factors. If you are a small startup and top level executive, then you decide based on whatever metrics you want. If you are a top exec at a medium-size company then you set the metrics and your directors make promote/fire suggestions based on those which you then approve or not. If you are a director or manager then you follow what is set by the execs and work with them to approve of your suggestions. If you want to promote multiple people but are limited in the number of people you can promote then it often comes down to who is going to perform better in the higher position. In larger enterprise companies there will specific policies (which may vary from department to department) and you'll follow those. Promotions and firing are both also sometimes highly contextual to the current macro environment. If things are going great and look like they will continue going great then you can afford to promote more people whereas in an economic downturn you will likely have to fire people who would otherwise be worth keeping.