You may have good performance reviews, but your managers may still say bad things about you if they don't like you or have a hidden agenda.

A lot of managers like me have very limited experience and extremely narrow technical expertise. Someone with more education, broader based experience, and research based talent would be able to take my job in a new york minute if I hired them as a subordinate. What I need is a flunky that is narrowly focused on RF networking, which no one really cares about anymore and is slowly being obsoleted.