Essentially, people (and AFAIK, all primates) have a built in behavioural system to take excess credit for wins and minimize blame for losses. The details are a nasty tangle of evolutionary psychology but the consequences, in groups, are blame deficits. These deficits typically manifest as a simultaneous doublethink mix of low morale and unrealistic optimism. That's the pathology.
Good personnel management is about leveraging this instead of fighting it. I recommend The Organization Man (1956) and Moral Mazes (1988) if you want to read on the topic and/or fall asleep fast but if somebody knows a more recent text on the topic, please suggest it.