Hi there, sometimes it is just a matter of perception about the person in reference. Someone let;s say Greg, makes a mistake or two at work or was even sometimes wrongly adjudged to have made a mistake and someone just escalates the issue and effectively kill Greg's confidence and give him a bad name at the same time. For this, there would be a perception problem surrounding Greg's output quality. And everyone will naturally expect him not to bring quality to the table.
In a nutshell, sometimes what we see is a result of confidence that had been murdered by a senior officer or colleagues, when in fact showing understanding and correction of the initial mistake would have helped Greg from the onset.