In my experience, the new top guy brings in his old lackeys because they complemented him, and made him look good, in the context of the top guy's previous company.

Hence they often turn out to be one dimensional, rather than rounded contributors - e.g great at bringing in projects on time even though everyone hates working with them, or great at technical due diligence/sniffing out skunk projects even though the new company's best work is in skunk projects.