Why ROAS is overrated; prefer MER, CAC, LTV

For years, ROAS (Return on Ad Spend) was the go-to metric for performance marketers. It was simple, clear, and instantly gratifying — the higher, the better. But as Mark Deruyter points out in our latest episode of The MarTech Matrix, that once-reliable metric has quietly become one of the most misleading KPIs in modern marketing.

We cover:

• The Problem with ROAS
• The Better Stack: MER, CAC, and LTV
• Measuring What Matters
• How AI Is Changing the Game
• Speed, Fit, and Impact: A New Way to Buy Tech

Takeaways

• ROAS is overrated. It relies on platform data and third-party cookies, which makes it unreliable in today’s privacy-first world. It measures spend efficiency, not profitability, and can create a false sense of success.
• Shift to MER, CAC, and LTV.
• Trust first-party data. Platform dashboards are directional only. Real insight comes from CRM and transaction data that connect spend directly to sales and retention.
• Retention is AI’s next frontier. AI can now identify inactive customers, predict churn, and trigger personalized outreach automatically. Retention automation is becoming the biggest growth lever for established brands.
• The modern marketer’s must-have skills:
• Buy technology based on speed, fit, and impact. If a tool can’t be implemented and delivering results within 30 days, it’s probably not the right one. Focus on solutions that make your team faster and smarter, not bloated with features.
• Collaboration beats silos. The best marketing teams align brand, creative, and performance to connect storytelling with measurable growth.
• Bottom line: Move beyond vanity metrics. Build a profit stack grounded in first-party data, AI, and metrics that matter — MER, CAC, and LTV. The future belongs to marketers who measure what actually drives profit, not just performance.

Chapters

01:27 How the marketer’s job changed (real-time, cross-team)

06:30 Brand’s rising importance & authenticity

09:02 Gut vs data (keep the art, validate the inputs)

12:36 Tools that accelerate marketplace performance (Stackline, Helium 10)

14:21 First-party truth over platform dashboards

15:32 Overrated metrics: ROAS → shift to MER, CAC, LTV

17:46 How to think about LTV at earlier-stage brands

21:32 Buying tech: 30-day implementation mindset; time-to-value

24:31 What vendors miss (research, economics, CFO proof)

30:42 AI’s impact: compress data → creative → execution

32:07 Acquisition vs retention (why retention wins next)

35:10 Future skills: data fluency, AI literacy, brand authenticity

38:23 Underrated channels: Affiliate & SEO (and AEO)

40:53 BFCM tip: have backup copy/creative variants ready