Personnel, financial and material mismanagement means that the government does not adequately (in other words: not efficiently and unjustly) manage the personnel, financial, and material means which it possesses.
Why is inadequate management so harmful?
If the government does not manage its means in an adequate and effective way, the government’s ‘running costs’ will increase disproportionately. The community will have to compensate the loss of money. This will cost the community an unnecessary amount of money which, in the end, the civilians must bring in through additional taxes.