Why is Performance Marketing Looking at Shrinking Returns?

The issue lies not in the engines of growth, but in how that growth is being interpreted; and acted upon. Metrics that once offered clarity are now hiding nuance, blending signals, and blurring true impact.

Which leads to a more pressing question: if the numbers feel reliable but tell an incomplete story, what exactly is performance measuring today?

The Measurement Problem: When “Performance” Isn’t Real Performance

For years, performance marketing has been built on a promise: measurable growth, attributable results, and clear ROI. But that clarity has always rested on a single assumption, that what is being measured reflects reality.

Increasingly, it doesn’t.

“Performance marketing is not suddenly broken,” Morris explains. “The problem is that too much of it is still judged through blended ROAS, platform-reported conversions and averages that hide the likes of marginal ROAS and incrementality.”

That distinction is not academic. It’s structural.

• Blended ROAS, from a Data-Driven Attribution perspective, tells how everything is performing together.
• Platform-reported conversions shows what the platform can see. 
• Averages smooth out volatility. 

But none of them isolates what actually changed as a result of incremental spend. That is where the illusion begins.

When optimisation is guided by aggregated metrics, activity that would have occurred anyway is often rewarded. Investment flows toward what appears efficient, rather than what is genuinely additive. Over time, performance seems stable on the surface, even as its underlying impact quietly diminishes.

This is also where many teams plateau; not because there are no gains left, but because they are no longer looking closely enough at where incremental improvements still exist.

Saturation, Automation, and the Shrinking Marginal Return

If measurement is the first fault line, market dynamics are the second.

Global digital ad spend is expected to surpass $1 trillion in 2026, a milestone that does more than signal growth. It marks a shift in the nature of competition itself. What was once an expanding field now feels increasingly finite, shaped by crowded, highly efficient auctions where every additional gain comes at a steeper cost.

According to Morris, the challenge stems from three forces: saturation, creativity, and structural limitations. “It is all three,” he says.

Saturation comes first. In mature markets, diminishing returns are not an anomaly—they are built into the system. The more spending grows, the harder it becomes to extract incremental value. Basic economic principles, from diminishing returns to demand elasticity, begin to assert themselves.

Then comes automation. As AI techniques like Performance Max take over targeting, bidding, and placement, differentiation shifts away from media mechanics. The levers marketers once controlled are now abstracted, optimised within black-box systems designed to maximise platform-defined outcomes.

And structurally, those platforms are doing exactly what they are built to do, i.e., optimise within their own ecosystems.

“Platforms still optimise brilliantly within their own systems,” Morris notes, “but not always for wider business value unless the inputs, constraints and measurements are commercially sound.”

In other words, the system itself is not broken. It is simply not aligned with broader definitions of success—unless it is deliberately calibrated to be.

Where this shows up most clearly:

• Auction pressure is compounding: Higher competition drives up costs faster than returns
• Automation is compressing differentiation: Targeting advantages are disappearing
• Platform optimisation ≠ business optimisation: What performs in-platform may not translate to real growth
• Marginal gains are harder to unlock: Scaling spend no longer guarantees proportional outcomes

The Creative + Commercial Reset: Where the Real Leverage Now Lies

For years, performance marketing distanced itself from brand and creative disciplines, positioning itself as a numbers game—analytical, precise, objective.

That separation is no longer sustainable.

Morris explains that performance marketing has evolved into something more than just a creative discipline. “It is now a Creative + Commercial Discipline,” he says.

“As automation takes more of the targeting, bidding and placement decisions, creative becomes one of the levers marketers still directly control; but it works best when paired with strong commercial inputs, continuous optimisation, and a deep understanding of customer needs.”

Creative without commercial clarity is noise. Commercial strategy without creative strength is invisible. But neither works in isolation.

The advantage now lies in how well these elements connect: creative quality, customer insight, data signals and the intelligent use of AI-led systems.

This is not about better ads in the traditional sense. It is about building systems where messaging, data, and context work together—where creative is informed by real insights, and where performance is judged not by clicks or conversions alone, but by contribution to business outcomes.

In that sense, performance marketing is not regressing. It is evolving towards something more integrated and, arguably, more demanding.

Rebuilding Performance Marketing Around Reality

If the current model is showing cracks, the question is not how to fix it incrementally, but how to rethink it entirely—while still recognising that many of the gains now come from compounding smaller improvements over time.

Morris is direct about what needs to go. He says, “I would remove overreliance on last click thinking, platform averages, siloed channel teams and any reporting that mistakes attribution for incrementality.”

In their place, he outlines a more grounded approach:

What to prioritise instead:

• Business impact measurement: Moving beyond platform metrics to real commercial outcomes.
• Marginal budget allocation: Understanding where each additional £ actually creates value.
• Integrated data systems: Connecting customer, product, and performance data into a unified view.
• Creative as a system: Building scalable, adaptable creative engines rather than isolated campaigns.
• Continuous optimisation: Relentlessly refining inputs, from audience signals to landing experiences, to unlock incremental gains

There is a through-line here. One that shifts the focus from optimisation theatre to actual impact. Because performance marketing is not becoming less “performant.” It is becoming less forgiving.

The easy gains have been extracted. The dashboards are no longer enough. And the systems that once delivered predictable growth are now exposing their limitations.

What comes next is not a collapse, but a correction. 

One that forces marketers to reconnect with fundamentals: measurement that reflects reality, strategy that extends beyond platforms, a deep understanding of customers, and a discipline that balances creativity with commercial clarity; supported by increasingly powerful AI-driven tools, but not defined by them.

Hear from Paul Morris, Senior Director, EMEA Performance Marketing & Web eCommerce at RS Group plc at Vibe Marketing Tech Fest (VMF), Manchester.