On the lookout
A study of over 1,700 employees conducted in 2012 by the American Psychological Association (APA) indicated that more than half of all employees intended to search for new jobs because they felt under appreciated and undervalued. http://www.apa.org/news/press/releases/phwa/workplace-survey.pdf
Perhaps the quickest way to get rid of someone is not to fire them but to not value or appreciate them. The problem is, we may not want to get rid of someone but they get rid of us.
David Zinger is a global employee engagement expert who uses the pyramid of employee engagement to help managers with engagement.