I don't know whether this is emphasized in the "mainstream" money manager evaluation industry, but your due diligence should include an investigation of your money manager's skill as a businessman (as opposed to investor), i.e. as the head of an enterprise that sells money management services.
A hedge fund management company can be analyzed as if it were a grocery store or lemonade stand or any other business. Does it spend too much on overhead, the most common cause of business death? What's the minimum AUM required to keep the lights on? Vendor relationships, esprit de corps, how long have the secretaries been there, etc. It's all fair game and relevant.
It's particularly relevant if you are evaluating a money manager who identifies himself as a value investor. If the guy spends his days searching for good businesses run by great managers, it's fair to ask whether the business he runs meets that description.