The "old guard" were just fine for explorers. You need the prospector to look into the ground with a gut feel and confident quess. A bunch of promo by a believer in their own prospecting ability to bring the gutsy investor is needed. Mines are different and as such new skills are needed. There are reasons that the previous people were not running Xstrata or Vale or Cliffs and as a company moves on and change, so do its employees. When you decide to go public with your company you give up ownership to the shareholder, and if those with money buy your company then the person with the most shares has the most control. The old guard needed to own the most shares to stay in control as when they sell their company to the public then they become an employee and as such will be made to move on.