According to this November 2011 article by Bright and Roberts via the Spencer Stuart website, 50% of all CEOs are planned to be changed post private equity purchase. This covers the period from 2004 and represents 155 changes. After the first year, the number of unplanned changes increases dramatically compared with those planned. Half the changes were due to under-performance and another 10% due to no agreement over strategy. This does not give confidence in assessing calibre of the management team, or agreeing strategy with those who know how to run the company.
The full paper is at IsTheManagementTeamRight