Mastering Marketing ROI in 2025: A Session with Measurement Leaders Tom Leonard & Ted Coxworth

Tactical frameworks for proving performance, defending budgets, and driving real impact

Disclaimer: The opinions represented here are those of the individual and do not necessarily represent those of their current or former employer.

With dashboards dominated by last-click attribution and algorithm-chasing ROAS targets, it’s no surprise that efficiency is often mistaken for effectiveness. Veteran consultant Tom Leonard is on a mission to correct that.

In a recent conversation with Tap In Digital, Leonard joined fellow measurement leader Ted Coxworth to unpack the costly missteps senior marketers keep repeating and how to course-correct. From cutting waste without panic to building a culture of incrementality testing, the duo offer a masterclass on measuring what matters in 2025 and beyond.

Watch the full interview below, or read on for a selection of key takeaways.

Key Takeaways

1. Rebalance your media mix to drive real growth. Focusing too much on last-click efficiency shifts spend toward non-incremental users and stalls your business.
   

2. Prioritize incrementality testing over attribution complexity. Geo holdouts and media mix modeling deliver clearer insights than multi-touch attribution ever will.
   

3. Run controlled go-dark tests to uncover true channel value. These experiments reveal whether a channel actually drives incremental sales or just takes credit for them.
   

4. Shift budget aggressively when results don’t justify the spend. When channels underdeliver in tests, redirect those dollars to higher-performing areas and accelerate growth.
   

5. Build a testing culture before scaling analytics complexity. Simple experiments and blended metrics give you fast, actionable insights without drowning in data science.

1. Don’t Let Last-Click Metrics Stall Your Growth
   

Focusing obsessively on last-click or last-touch performance metrics can create a false sense of efficiency while your business growth plateaus. If you allocate budget based on what shows the best immediate ROI, you’ll pour money into capturing existing demand rather than creating new demand. This might boost short-term ROI on paper, but as Leonard notes, you’ll stop reaching new customers. The key is to invest in upper-funnel channels that drive brand awareness and incremental new buyers, even if they don’t get “last-click” credit.

“You stop growing because you are no longer reaching new customers. You are accidentally pushing all of your dollars toward non-incremental users, people already on their path to purchase or who simply don’t need an ad to make the purchase... The marketing team [keeps] reporting amazing efficiency gains, but the CFO is like, ‘We’re losing share, we’re not growing year over year…’ That’s the classic disconnect of just putting dollars in front of people that are going to convert, not causing people to convert.”

Adidas learned this lesson the hard way. By 2019, Adidas had been over-investing in performance ads due to last-click attribution reports that made channels like paid search look insanely efficient. But when a technical glitch forced a temporary halt of Adidas’s search ads in one market, sales didn’t drop at all, revealing that those “high-ROAS” ads weren’t truly driving incremental revenue. In fact, Econometrics showed that brand-building channels were responsible for 65% of sales.

If you want help moving beyond last-click attribution, Tap In Digital can help. Contact us today.

2. Prioritize Incrementality and MMM Over Multi-Touch Attribution

   
   

In the era of privacy constraints and complex customer journeys, traditional multi-touch attribution (MTA) modeling has lost much of its luster. Leonard is blunt about it. He says obsessing over perfect attribution across every touchpoint is often a waste of time. Instead, he urges marketers to double down on incrementality testing like controlled holdouts, geo experiments, and media mix modeling (MMM) to measure what truly moves the needle.

“I’m very bearish on MTA and more or less think it’s a waste of time… For a lot of brands, platform-based last-click attribution is good enough for day-to-day decision-making so long as it’s informed by incrementality testing and media mix modeling… I put the least stock in the attribution side, and the most in incrementality testing. I think MMM can be really nice for an always-on view of each channel’s contribution.”

Direct-to-consumer brands are increasingly adopting this approach. For instance, Resident, the company behind Nectar Mattresses, implemented an MMM solution to guide its budget allocation. The payoff was huge, resulting in a 20% increase in revenue with the same blended customer acquisition cost, after just five days of implementing the MMM model. By moving beyond last-touch attribution and embracing an incrementality-first mindset, the Nectar team identified which channels were truly driving new sales and optimized spend accordingly.

3. Use ‘Go Dark’ Tests to Expose True ROI

How do you convince a skeptical organization about the value of a marketing channel? Leonard suggests “go dark” tests, intentionally turning off a channel or campaign to measure the value it truly provides. For a quick win, he recommends starting with branded paid search. Often, the clicks your branded ads were getting simply shift to organic clicks when ads are off, indicating those ads weren’t adding new revenue. Seeing that pattern can be an “aha” moment for the team, sparking the realization, “If this is true for branded search, could it be true for other channels like retargeting or certain display ads?”

“For most brands, incrementality testing, specifically go dark tests, are a great place to start. Think of branded paid search as a test case, because everyone sort of understands that branded search is probably not incremental… Do a go-dark test and see what happens to your top-line. Watch organic search: do you see that perfect inverse correlation where branded search visits drop, and organic visits rise by the same amount? You get such beautiful visualizations, and it gets the organization thinking, ‘If this is true for branded search, could it be true for retargeting?’”

Auction platform eBay validated the value of the “go dark” strategy in its own testing. In a controlled experiment, eBay turned off its branded keyword search ads in certain regions, which changed hardly anything. Customers who would have clicked the ad simply clicked the organic search result instead. A report of the experiment found that “brand keyword ads [had] no short-term benefits,” as most shoppers would have found their way to eBay without the ad. Armed with this evidence, eBay dramatically cut back on wasteful ad spend.

4. Cut Waste and Reinvest in What Works

   
   

Many marketing leaders find it terrifying to disable channel spend or cut budgets because of potential sales dips. Tom acknowledges this fear of short-term loss, but flips the script: What if the real risk is wasting money on something that isn’t working? If you see no drop, you just found money to reallocate into better uses. Tom also notes the human element: marketers’ incentives and ego can be tied to managing large budgets, so it’s important to realign rewards around growth outcomes, not spend levels.

“There’s a fear: ‘We may lose so much [if we stop or cut a channel]...’ But consider, say you’re a $100M brand and you think maybe 10% of revenue is driven by Facebook. If you do a geo holdout test, you’re not going to lose all $100M. Maybe worst case, turning Facebook off might cost $10M in the short term. Still huge, but is the opportunity cost greater if you never find out? What if you turn it off and lose a big chunk? Then you know Facebook was undervalued and you can double down. Or if you lose nothing, you can redistribute those dollars and find something that drives growth.”

In 2017, P&G discovered that a lot of its digital ad spend was ineffective, as ads were either not being viewed long enough or were targeting the wrong audiences. In response, P&G cut $200 million of digital ad spend in that year. Many in the industry held their breath, but P&G’s sales did not tank. In fact, the company reported that by removing poorly performing ads and fraudulent placements, it increased its marketing reach by 10% while spending less. P&G then reinvested the saved budget into higher-impact channels like quality TV, audio, and e-commerce media, rather than simply pocketing the savings.

5. Embrace Simple Metrics and Continuous Experimentation

   
   

According to Leonard, one of the most dangerous pitfalls marketing teams can fall into is oscillating between oversimplification and overcomplexity. Vendor relationships and accurate measurement are important, sure, but it’s important to find a healthy middle ground. For Leonard, there’s a temperate in-between, where efficiency is measured by simple metrics and teams embrace a culture of thoughtfulness and experimentation.

“At first people oversimplify…And then the minute they realize, wait a second, maybe there's holes in that armor… [they think], ‘I need a million dollar check to go find a couple data scientists, an MMM vendor, an incrementality testing vendor… People go from too simple to too extreme, whereas I think there's a lot of nice in-between things, where it's like, ‘Do you ever look at just blended efficiency metrics, like a total blended CAC or a blended MER?’”

Simple metrics paint clear pictures, and even major brands have come to embrace that. The marketing team at James & James has adopted Marketing Efficiency Ratio (MER) as its North Star metric, essentially looking at total revenue versus total marketing spend. This broader perspective immediately gave them a reality check. As the company’s CMO Tristan Cameron shared, platform-specific ROAS had created an overly optimistic picture of performance. When they switched to MER, it became clear “that just wasn’t the reality for our bottom line.” As AdExchanger’s James Hercher put it, it provides the company a rolling benchmark rather than a one-off way to measure campaign performance.

Multiplication By Subtraction

Simplifying your approach to marketing can seem like a counterintuitive way to make a bigger impact, but there’s undeniable wisdom in what Tom Leonard has to say. Countless companies have implemented the same strategies, and they’ve left behind a trail of success. If you want to keep up to date with Tom, you can find him on LinkedIn.

And whether you're trying to win over finance, clean up messy reporting, or finally break your addiction to last-click attribution, the playbook is clear: test boldly, measure what matters, and reallocate with confidence. Tap In Digital helps leading marketers do exactly that. When you’re ready to stop guessing and start growing, we’re here. Contact us today.