Every signal is measured against two things: where the product was before the deal, and a rival that wasn't bought. Divergence is the metric.
Mock data, invented for the argument. Companion to the essay → read it here
Nothing here is broken. Every line is still moving. That's exactly why it's dangerous: the product that's decaying and the product that's healthy both keep shipping. The only difference is the slope, and slope is the thing a status update never shows.