Let me introduce you to be Peter principal: As long as you do your job well, you get promoted. On the flip side this means that eventually you arrive at a job you don't do well and that's where you stick because you can't return to your old position but neither will you get fired because you work for the company too long. That's why there are many people in middle management who did their job well until they had to manage others which isn't part of their skill set.