So when I was at Google, hiring was not done by the groups with the headcount. Instead they were hired centrally and then later dispatched. The reasoning for this is that for a manager, someone who is just good enough will generate utility and thus should be hired. The central hiring is supposed to enforce companywide higher levels.

I wonder if stack ranking is the same but for getting bad people to leave? Even a weak employee can be better than no employee for a manager...