Key Performance Indicators (KPI) or any other similar packaged goods such as Critical Success Factors (CSF) are often nice concepts as long as they do not escape into the real world.
Let me start with my own misery. For commuting to work I use the train between Oxford and London via Reading. My station is between Reading and Oxford. So I use the a fast train between London and Reading and a stopping one between Reading and Oxford. Now my train company has decided that when the train is running late to convert the stopping service into a fast service about two times week and as such my journey gets one hour longer. The really annoying thing is that when they do it they just announce it near the end of the journey as great customer service as they have listened to their customers.
Being of an inquisitive mind I called an architect working for that company. He told me that this idea was really seen as the golden solution as all customer surveys always pointed out delays as the main problem. By not serving the local stations or just skipping a few the train will be back on time. Wile the logic here is 100% true and the intent of customers was also captured and translated in the right KPI, the execution creates the opposite of the intention of more satisfied customers. The problem here as well in many other similar situations is that the reality is a rather complex system, while KPI and similar measures only work in a simpler closed system.
As such KPI’s should always only be used in a defined relationship with certain processes where they have been vetted. This usual lack of vetting is why customer service satisfaction scores will always vary between seasons even if the service was performed in the same way, as a customer will always rate a service offered on rainy day lower than one on a sunny day.