Mr. Chandra

We should not see two statements as mutually exclusive statements. Both of them are correct in different contexts.
 
We need to measure things to manage them effectively. Especially we need measurements for trends, analysis and performance reporting. (Peter Drucker)
 
However, if any business rely exclusively on their performance metrics and assume everything hunky dory some surprises are bound to happen.
 
Let us consider an operations where the SLAs are always Green. If the operations head assume that the customer is super happy with the service and do a CSAT- it may throw some surprises. This we call it as watermelon effect. Where SLAs are Green and the CSAT is Red.
 
The other example can be a product sales exceeding the targets for several quarters. If the business assumes too much of customer loyalty towards that product and doesn’t innovate enough- they are in for surprise when one fine day a better product enters the market.
 
What we cannot measure in the above examples (and which is important for a Business) is  Human behaviors, Relationships, Customer Requirements and Expectations. (Deming)
 
So we should have good measurements in place to manage the Known- Knowns. At the same time we need to cognizant of the fact that some unknowns/unstated needs exist in the business which we have to manage even without Metrics.