It fascinates me that succession from a successful CEO to the chosen successor almost always goes badly. This phenomenon isn't limited to the CEO level -- I've seen highly successful CMOs followed by handpicked successors who also seem to have no clue as to why their predecessor did so well. I think it comes down to a lack of mentoring combined with misconceptions. People with different backgrounds often think their predecessor was lucky rather than smart. With Steve Jobs, it was always known that replacing him would be incredibly difficult.