As a manager (now retired), I was pressured often to give rankings to justify who we wanted to keep and who the company wanted to let go. And, salary and the ability to lower payroll costs played a big role. So, there were high performing employees whose ranking was lowered. While younger and cheaper employees were high graded even though their performance did not justify the ranking. It was not necessarily an objective look at performance. It was determining the end result and working the rankings backwards.
Reposted from @3vvb+1cqyboth so that everybody can see what kind of cr-p is happening here.