Please make the following in red clear for me.
Mathematics is a closed system, so we know we are right. It's logical. But now let's analyze something that is not pure math: the performance of your company over the past decade. What do I include in my analsis, and what do I leave out? For example, the weather: Should we gather data on temperature and plot that against a measure of unit performance? If I say yes and you say no, which one of us is right? And what is our measure of unit performance?
I'm not sure what "measure of unit performance" is saying. Is it saying "a level of performance of departments in the company"? What's the exact meaning of "measure" and "unit" there?
It depends on what "unit" of your company you are measuring. If you want to evaluate a production area, you might measure number of widgets made per shift. Or the number of errors/rejects. Or the amount of injuries.
Sales people would be measured by number of sales in dollars, or perhaps the margin (profit) on sales they have made. Accounting may be measured on the number of reports they can create and how accurate they are.
The idea is that every function in a company has some way that it can be measured.