This also depends on the definition of "performance". A top performer at one company may be considered useless at another. It all depends on who they hired. The

This also depends on the definition of "performance". A top performer at one company may be considered useless at another. It all depends on who they hired. Then of course you can have poor management - someone may not be great a context switching and if manager keep asking to look at different stuff every day or if there is a ton of junior developers needing help with everything, then you may not have mental capacity to do quality work on the stuff you are measured by.