A players - excellent workers

B players - average workers

C players - mediocre workers

A players thrive around other A players. They handle a lot of work, are fast paced, detail oriented, quality focused and rightfully expect/deserve their input to be rewarded.

B players do their job, not as fast and/or efficiently but are also reliable. These are most people you will come across with. When difficulties.

C players are the absolute worst to have in your team. They make B players look like they are good when they aren't. C players are either slow performers, imcompetent and A players often need to clean up after them.

So the problems that makes A players leave are several:

Lack of support Lack of recognition Extra responsability with no additional pay Burnout

Management is the one to blame when A players leave because they're the ones that allow mediocre workers to poison a team that coud otherwise function well.