The idea
One number tells you nothing. Two numbers tell you what to do.
Your margin change is really two changes added together. One part came from outside: input prices, freight, demand, a supplier's own trouble. The other part came from inside: what you sourced, what you ran, what you held, how you staffed it.
Reported together, they cancel out into a single figure you can only shrug at. Pulled apart, they give two different instructions. Volatility you cannot control, you hedge and diversify against. Inefficiency you can control, you fix — and the fix is worth a known amount.
Doing this needs structured data, versions, and a record of what was decided and when. That is why the first work is on your data, not on a slide.