93% of employees say that working with a low performer has decreased their productivity or made them want to change jobs. The resulting loss in productivity can cost companies between $450-500 billion a year.
The biggest cause of this is when the low performer goes unchecked for a long time. Other workers see that it's ok to do almost good enough and get by so they tell themselves don't work so hard.
If the over performers goes unnoticed and the under-performers go unchecked it will cause productivity to plummet.
We all have a sense of pride in our work. We all have an ego that came with the human package. If I'm working hard and you are working with me doing half ass work I am going to want to be recognized for my work or you get punished for your lack of work.
Here's a simple solution; As a leader you can prevent this by simply paying attention and making mention of the over performers. Recognize them publicly in front of the other workers. Thank them for doing a good job. That will do two things, 1. It will stroke the workers ego (which we all need from time to time) and 2. It will show the other workers that you do notice what kind of work they do and they will step up to the plate also.
See something say something, good luck.