Both of those books showed a relationship between Michael Eisner and the late Frank Wells as one where Eisner would go off into a bout of mental and verbal diarrhea, and then Frank Wells would jump in, clean it all up, and get it ready for prime time, as it were. After Wells died, Eisner lost that binary partner that took his ideas and work and made them functional elements of a grand machine.
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In defense of Eisner, and I think this a very important point since so much of Eisner's later tenure was defined by conflict with Jeffrey Katzenberg, is that he was correct not to give Katzenberg Frank Wells' job. Katzenberg is another high-powered, hard-charging executive type, and that would have likely either only amplified Eisner's problems, or caused so much internal conflict that it could have ripped Disney apart.
But again, in defense of Katzenberg, he appears to be more aware of this limitation than Eisner was. Katzenberg is famous in Hollywood for surrounding himself with powerful women -- a group that is more than slightly underrepresented in most studios. This drive to associate with those that are not simply more hard-charging white guys has undoubtedly played a large role in his ongoing success.