Don't be disruptive

As a manager at Amazon, I witnessed really bad behavior during our annual OLR reviews which hurt our staff and no one in HR or senior management seemed to care. One particularly bad case involved a manager who came to the OLR meeting without having done his homework on an SDE who transferred into our group. He proposed a very mediocre rating for her and thought that would be good enough since he didn't actually have any performance data. However, one of the few very good managers (who actually cares about his employees, which is rare in Amazon) then called him out for this since she previously had stellar ratings in her last group. He agreed to follow-up and correct her ratings but never did. When the good manager later asked him whether he "closed the loop" and corrected her rating, all of the bad managers and even our director ganged up to label that good manager as "disruptive" for daring to try make our group actually measure performance data rather than dishing good reviews only to their friends. He eventually left Amazon, which was a huge loss. 

The only lesson you can get from this is that you can't ever win by doing the right thing at Amazon since the number of bad managers far exceeds the good ones and they'll always gang up to protect themselves and avoid being held accountable for their unethical behavior.