Why the usual metrics cannot answer this
Ask a marketing team whether AI helped and the answer arrives quickly: we produce four times the content. That is a real change and it is not an answer.
The problem is that output is an input, and marketing's job is outcomes. Four times the content with the same distribution and the same attention produces four times the content, not four times the result. In a channel with fixed attention it can produce less, since undifferentiated volume performs worse per item.
And the outcome metrics that would settle it are exactly the ones already contaminated. Conversions, pipeline and revenue move for reasons unrelated to how the copy was produced, and marketing's attribution problem predates AI entirely.
So three failure modes recur when teams report on this.
Measuring activity and calling it impact. Pieces published, variants generated, hours saved. All real, none of them evidence that anything improved.
Attributing a good quarter to the tool. The quarter had other causes, and the tool is the most recent change, which is not the same as the cause.
And not measuring at all, on the reasoning that everyone is doing it. That is a decision to spend without knowing, which is precisely the position the function exists to help others avoid.
What can actually be measured is narrower and more useful, and it is the next step.

