If you say that someone has mishandled something, you are critical of them because you think they have dealt with it badly.
例句
She completely mishandled an important project purely through lack of attention...她之所以徹底搞砸了一個重大項目純粹是因為不夠上心。The judge said the police had mishandled the siege.法官說警方對圍攻安排不當。