I would say those mistakes involved recruiting the wrong managers who needed replaced far earlier than they should have.
Those managers were to various extents given their head in signing players that their successors then moved on at huge cost.
Not many of the managerial appointments were widely criticised at the outset, indeed most if not all looked visionary.
Its just a shame football isn't played on paper :-)
We are also not alone in the difficulty of regular duff managerial appointments and the subsequent revolving door of player trading that those involve.
Hearts, Rangers & Dundee United immediately spring to mind
Whether by luck or improved process we have seen managerial stability through Stubbs & Lennon which has led to player stability and not accidentally improved performances.
Hopefully it is improved process but it would be greatly ironic if when Lennon moves on it had proved to be luck
It will be painful viewing for all if Leanne's status is transformed from Messiah to pariah after a few iffy managerial appointments.