What are some ways to avoid incompetence when hiring a new manager?

First of all, be certain that you have accurate job specifications.  Outdated or otherwise inaccurate job specifications can result in honest misunderstandings regarding what the job entails and end up causing confusion about the qualifications and traits that will most likely result in a longer-term successful hire.  Objectively review resumes to assess the experience/knowledge base of each applicant and select only those who actually appear to “fit” the established criteria.  Then, use a phone screen comprised of questions that enable you to determine employability factors of the potential finalists (why are they on the job market, do their career stories make sense, what are they seeking in their next career step, etc.)  If possible, use a validated aptitude/personality dimension assessment to further narrow the field and ensure that each finalist is genuinely capable and suited for the management job.  For the face-to-face interviews, use a standardized behavioral-based questionnaire that is based on the actual job that needs to be done.  Ask everyone you interview the same questions in the same order.  Take notes.  Be sure to give each candidate time to talk.  Having a weighted “scoring system” also facilitates the objective aspects of the interviews.  When it is your turn to talk, don’t sugar-coat what the management job entails.  Be honest and watch the
body language and reactions to the stated challenges that you feel the new manager will face.  Review your notes and your scores as objectively as you can.  And finally, use your gut.  Which candidate most impressed you as having the qualities that will work well with your other team members and with you?