A quick primer
The official diagnostic tool for this split is the same keyword-level Quality Score components used to diagnose ROAS. Ad Relevance covers traffic quality: how well the ad matches the intent behind the keyword. Landing Page Experience is a separate factor about what happens after the click.
If Ad Relevance is healthy and conversion is still low, the problem sits on the site side. If Ad Relevance is low, the wrong people are landing on the page in the first place.
What to check before you touch anything
- Ad Relevance and Landing Page Experience checked separately, not as one blended score.
- Whether search queries (via the Search Terms report) match the ad, and the ad matches the page.
- Whether there's enough click volume for a reliable read.
- Whether the gap between the two components appeared recently.
Possible approaches
- If Ad Relevance is low, work on targeting and copy before touching the site.
- If Landing Page Experience is low with healthy Ad Relevance, focus on the page itself.
- If both are fine, look at offer competitiveness, trust, or checkout issues instead.
- Check this by segment, not just account-wide.
- Treat Quality Score as a pointer, not a final verdict.