So, you hire a new manager to run a key department in your company based on a strong skill set, resume, references and interview. He has a distinct management style and philosophy, but the existing staff was hired by the last manager who was fired for poor performance. Most of the staff have bought in to the new manager and are trying, but some have not bought in and others have decided to move on. The early results are disappointing, but for the most part, not unexpected.
Do you demand that the new manager adopt the style and methods of the last one, or do you expect him to do what you hired him for? When you're paying good money, and your organization's long term success is on the line, do you want the guy on the resume, or the guy you just fired? After all, if the previous guy's style/system and personnel decisions were sound, you wouldn't have fired him to begin with.