A graph can show improvement while the people doing the work feel less able to continue.

Numbers can rise while the thing producing them is being used up. Output measures the result and says nothing about what it cost in sleep, goodwill, or the reserves people draw on when something goes wrong. A line that climbs while everybody quietly runs down looks like success right up until it stops, and whatever is not measured tends to get spent first.

When results improve, ask the people doing the work how the last month felt. If you are the one being measured, say what the number is costing while it is still a sentence rather than a resignation.