Every creative intelligence tool is under pressure to say the same sentence: our AI knows which ad is going to win. It is a good sentence. It is also, as far as we can tell from our own data, not true.
So we tested it properly before we put it on a website.
What we ran
We took creative embeddings across a large pool of ads and asked a simple question: given only the creative, can we predict how it will perform?
The first result looked spectacular. Pooled across the whole set, a classifier separating high-CTR from low-CTR creative hit an AUC of 0.94. If you stop there, you have a product claim.
We did not stop there.
Where it went
The pool contained ads with different objectives, from different brands, at different spend levels. Traffic campaigns have structurally different click-through rates than conversion campaigns. Some brands simply get more clicks than others, regardless of what the creative does.
An embedding encodes all of that. It knows a traffic ad looks like a traffic ad. So the classifier was not learning "this creative is persuasive". It was learning "this is a traffic ad from a brand with a high baseline", and the CTR label was largely a restatement of the same fact.
When we demeaned by brand and objective, so that the model had to explain variance within a brand and within an objective, AUC fell to 0.36. Below chance. The signal was base rates wearing a costume.
What embeddings are actually good for
This is not a case against embeddings. It is a case against one specific claim.
Embeddings are excellent at similarity. Which of our ads are close to this one. Which competitor creative occupies the same space as ours. What has this account never made anything near. Those are all questions about geometry, and geometry is exactly what a vector space gives you.
They are poor at forecasting, at least at the volumes most advertisers operate at, because performance is dominated by factors the creative does not contain: audience, budget, bid, seasonality, offer, landing page, and the platform's own delivery decisions.
What we say instead
Marxx tells you what ran, what is decaying, what your competitors are doing, and what your account has never tested. Diagnosis and coverage. Every one of those is verifiable against the data the same day.
We do not tell you which ad will win, because when we checked, we could not.
If a vendor tells you otherwise, ask them for the demeaned number.