The Asset Group Dilution Problem
How Performance Max spreads your budget across low-intent placements and what to do about it.
Performance Max promises to find customers wherever they are. The reality is more complicated: your budget gets spread across every Google property, and you have limited visibility into which placements are actually driving value.
This is the asset group dilution problem. And it's costing ecommerce brands more than most realise.
The core issue: PMax treats Display Network impressions and Shopping clicks as equivalent signals for optimisation, but they have fundamentally different commercial intent.
Where Your Budget Actually Goes
Performance Max can serve ads across:
- Google Shopping (high intent)
- Search (variable intent)
- YouTube (awareness, low direct intent)
- Display Network (awareness, often very low intent)
- Discover (browsing, low commercial intent)
- Gmail (variable, often disruptive)
The algorithm decides the mix. You provide assets and budget. Google determines allocation based on its prediction of conversion probability, but that prediction doesn't account for margin, customer quality, or long-term value.
High-Intent Channels
Shopping and branded Search capture demand that already exists. These users are actively looking to buy.
Low-Intent Channels
Display and Discover create impressions but rarely drive direct conversions. Budget here often subsidises awareness without clear attribution.
The Dilution Mechanics
Here's how dilution typically manifests:
Cheap Impressions Look Efficient
Display placements are cheap. They bring down your average cost-per-impression, making the campaign look more efficient than it is. But impressions don't pay invoices.
View-Through Attribution Inflates Results
Someone sees a Display ad, later searches your brand and buys. PMax claims the conversion. That customer likely would have bought anyway. You've paid twice for one sale.
Shopping Gets Starved
When the algorithm finds cheaper conversions (even if lower quality) on other channels, it shifts budget away from Shopping. Your highest-intent channel gets underfunded.
The Visibility Gap
Google provides limited reporting on PMax placement breakdown. You can see aggregate performance, but understanding exactly where your budget goes requires inference and third-party scripts.
This opacity isn't accidental. If advertisers could see that 40% of their budget was going to low-performing Display placements, they'd demand controls that don't currently exist.
The less you can see, the less you can question. PMax reporting is designed to show outcomes, not allocation decisions.
What You Can Actually Control
Despite the limitations, there are levers available:
1. Asset Group Segmentation
Create separate asset groups for different product categories or margin tiers. This gives Google clearer signals about what should be served where.
2. Audience Signal Strength
Strong audience signals (customer lists, high-intent remarketing) help the algorithm focus on qualified users rather than casting wide nets.
3. URL Expansion Controls
Turn off final URL expansion to prevent PMax from sending traffic to pages that don't convert. This removes one variable from the equation.
4. Placement Exclusions
Review the (limited) placement reports and exclude sites that are clearly low quality. This is a slow process but compounds over time.
5. Separate Standard Shopping
Run Standard Shopping alongside PMax for your core products. This ensures Shopping doesn't get starved and gives you comparison data.
The Commercial Reality
Asset group dilution isn't a bug. It's how PMax is designed to work. Google's incentive is to fill all its ad inventory profitably. Your incentive is to acquire customers profitably. These objectives overlap but aren't identical.
The brands that perform best with PMax are those that:
- Understand that reported ROAS includes inflated attribution
- Monitor contribution margin, not just platform metrics
- Maintain Standard Shopping for critical product lines
- Treat PMax as one channel, not the only channel
The solution to dilution isn't abandoning PMax. It's understanding its limitations and building structure around them.
Questions to Ask About Your Account
- What percentage of PMax conversions are view-through vs click-through?
- How does PMax ROAS compare to Standard Shopping for the same products?
- Are you running brand exclusions in PMax?
- What does your incrementality look like when PMax is paused?
- Are asset groups structured by commercial priority or just product type?
Related Reading
Want to understand where your PMax budget actually goes?
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