You can avoid this by making it a deep dark secret that you are firing the lowest 5% --- or that the reason why certain people are put on a PIP, subject to a "r

You can avoid this by making it a deep dark secret that you are firing the lowest 5% --- or that the reason why certain people are put on a PIP, subject to a "resource action", or "has found new opportunities outside of XXX" was due to the the fact that they fell into the lowest 5% bucket. I've seen this work at a past company at least reasonably well. A few people knew about the policy, but it wasn't something which was top of mind by all of the engineers, to the point where it started adversely affecting the company culture. (BTW, I'm not saying it was a good thing; and I'm glad I'm no longer working there. But if you don't worry about silly things like ethics, and only worry about maximizing shareholder value, it's a strategy that might work for a while.)