When metrics become monsters

There’s an old economics gem called Goodhart’s Law: “When a measure becomes a target, it ceases to be a good measure.”

Sounds academic, but here’s the translation: the second you obsess over a number, you break it. And in marketing, we break numbers all the time (ROAS, CTR, CAC, MQLs) because we freaking worship them, screenshot them, and put them in decks with confetti emojis. And in doing so, we often forget that these numbers were supposed to guide us, not define us.

In today’s “outcomes era” of advertising, everything has to prove itself instantly. That’s great for dashboards… not always great for long-term growth.

Because when the metric becomes the mission, we risk creating success on paper and stagnation in reality.

Let’s start with a little parable.

A direct-to-consumer skincare brand managed to pull a glorious 6:1 ROAS on Facebook. Champagne corks flew. The marketing team basked in glory. However, they did it by relentlessly blasting their most loyal customers with their top-selling products.

So yeah, the metric was glowing, but the brand was quietly digging its own grave. Why, you ask?

• Product tunnel vision: bestsellers hogged the spotlight, cross-sell opportunities died.

• Audience fatigue: targeting the same fans over and over until the ads became wallpaper.

• Innovation suffocation: new launches never got traction because algorithms kept backing old winners.

• Market share leakage: while they milked their loyalists, competitors waltzed away with fresh customers.

The result? A dashboard that looked pristine, and a growth engine running on fumes.

And this isn’t just a hypothetical scenario. It happens all the time.

Goodhart’s Law is not picky. It’ll haunt any channel where metrics rule unchecked. This can look like:

• Email: clickbait subject lines for the sake of open rate… cue unsubscribes.

• SEO: stuffing so many keywords into a blog that it reads like a ransom note.

• Social: chasing engagement until your brand voice sounds like an unhinged raccoon on TikTok.

• Media buying: optimising for the cheapest clicks, only to attract bots, bargain hunters, or people who will never actually buy.

The trap is universal: what looks like performance often masks decay.

So, if the problem is so obvious, why do we keep doing it?

Blame a few familiar villains. Finance pressure is a big one. Every dollar spent has to have receipts, so marketers get squeezed into chasing whatever number looks best in a boardroom slide.

Then, of course, there’s algorithm worship. We hand over the wheel to platforms and let them tell us what “works,” forgetting that their priority is platform revenue, not ours. Add in short-termism, where quarterly targets devour any hope of long-term thinking, and you’ve already got a perfect storm.

And finally, there’s dashboard addiction. Those neat, tidy numbers make us feel in control, even when they’re quietly leading us astray. Chasing a metric feels good, like candy. But too much candy? We all know how that ends.

When you let the dashboard run the show, the costs pile up fast.

Your best customers get sick of seeing the same ads over and over. Your product line starts to stagnate as you double down only on the things that “perform.”

The growth pipeline clogs because you’re no longer feeding it with new audiences or fresh ideas. And while you’re patting yourself on the back for hitting this week’s numbers, your competitors are happily eating your lunch. You win the battle -the metric - but you quietly lose the war, which is the actual market.

How to break the cycle

Okay, enough doom (I’m sorry, I know I’m awful good at that.) Here’s how to stop letting Goodhart’s Law punk your campaigns:

1. Ladder up. Don’t let a metric float around unattached. If it doesn’t connect to a real business outcome: growth, retention, brand health - it’s just noise.

2. Budget for “bad” numbers. Exploration looks ugly at first. New channels, new audiences, and new creative won’t beat your proven winners right away. That’s the point.

3. Treat metrics like gossip, not gospel. ROAS is a rumour. CTR is tea. They hint at what’s happening, but they’re not the truth. Dig deeper.

4. Zoom out. Short-term efficiency feels great, but long-term metrics like lifetime value, market share, and brand strength tell you if you’re actually building something durable.

5. Mix exploitation with exploration. Steal a trick from decision science: use part of your budget to squeeze what’s working, and part to discover what’s next. Balance is everything, baby.

Goodhart’s Law is a reminder that if you worship the metric, you’ve already lost sight of the mission.

Marketing success isn’t a high ROAS screenshot; it’s a brand that keeps growing, evolving, and winning customers for years to come.

So yeah, hit your numbers. But don’t confuse them with the point. Otherwise, you’ll end up like that skincare brand: flawless dashboard, flaky future. The real flex is being the marketer who knows the difference.

-Sophie Randell, Writer