Quality Score is one of the highest-leverage variables in Google Ads performance. A low Quality Score forces you to pay more per click and lose auctions you could otherwise win — meaning the same budget delivers fewer impressions, fewer clicks, and fewer conversions. The root cause is almost always the landing page.
Google determines ad position using Ad Rank:
Ad Rank = Quality Score × Bid
This means Quality Score and bid are interchangeable levers. A campaign with a Quality Score of 6 and a $3 bid has an Ad Rank of 18 — beating a competitor with a Quality Score of 3 and a $5 bid (Ad Rank 15). You can win auctions without outspending competitors if your Quality Score is higher.
Conversely, low Quality Scores force you to raise bids just to maintain position, inflating CPC and eroding efficiency.
Google evaluates three factors, each rated Below Average / Average / Above Average:
| Component | What It Measures | Primary Lever |
|---|---|---|
| Expected CTR (eCTR) | Likelihood someone clicks your ad given the keyword | Landing page relevance & ad copy |
| Ad Relevance | How closely the ad matches search intent | Ad copy, headline alignment |
| Landing Page Experience | Quality and relevance of the destination page | Landing page content, speed, UX |
It may seem counterintuitive — eCTR sounds like an ad copy problem. But Google's eCTR model incorporates historical performance signals that include post-click behavior. A poor landing page that fails to convert trains Google's algorithm that clicks from your ads don't lead to good outcomes, which suppresses predicted CTR over time.
Diagnostic signal: If eCTR is "Below Average" but Ad Relevance is "Average" or better, the ad copy is fine — the landing page is the problem.
This pattern was observed directly in the [1] account: Quality Scores of 4–5/10 across the retirement campaigns, with eCTR rated "Below Average" and Ad Relevance rated "Average." The ads were well-written; the landing pages were not converting.
Low Quality Scores cause impression share loss due to rank, not budget. This is a critical distinction:
When impression share loss is predominantly due to rank and the account is not budget-constrained, the fix is Quality Score improvement, not more spend. Throwing budget at a low-Quality-Score account is wasteful.
Google's Optimization Score (0–100%) correlates with eCTR. Accounts with low optimization scores tend to have lower eCTR because they're leaving ad strength improvements on the table.
Target: Optimization Score > 80%
Key actions to raise optimization score (and eCTR):
- Fill all available headline slots (max 15 for RSAs)
- Fill all available description slots (max 4)
- Add sitelink extensions (target 5+)
- Apply Google's keyword and asset recommendations selectively
- Use broad match + Smart Bidding where conversion history supports it
When a campaign shows high CPC, low impression share, or stalled conversions:
Landing page quality is outside the direct control of the ads manager. When Quality Score analysis points to a landing page issue, it must be escalated to the account manager with a clear explanation:
"We're losing impression share due to low Quality Scores. The eCTR component is below average, which indicates the landing page is the bottleneck. Improving the landing page will lower our CPC and increase our ad position without increasing spend."
This framing helps account managers understand that landing page investment has a direct, measurable ROI in reduced ad costs.