These companies also have a general policy of 5-10% 'natural' attrition a year, i.e. they expect a large percent of people to leave. The bottom 5% of stack ran

These companies also have a general policy of 5-10% 'natural' attrition a year, i.e. they expect a large percent of people to leave. The bottom 5% of stack ranked folks are almost always targeted for this attrition. They're put on 'performance improvement plans' that demand daily monitoring and check-in, and other onerous rules designed to make them quit. With stack ranking the bottom bucket is basically assumed and designed to be ejected from the company every year.