The account was not underperforming. It was under-reporting.

I took over an account where reported conversions did not match backend orders, which made the performance data unusable for decisions.

The campaigns were optimising toward a signal that reflected roughly two thirds of actual revenue. Smart bidding works toward the conversions it can see, so a third of the revenue was invisible to it. Every budget and bidding decision downstream was being made on a number that did not describe the business.

Audited the GA4 and platform-level setup, identified where the events broke, and rebuilt the measurement layer. Only after the numbers reconciled did I touch campaign structure.

Not optimising first. There is always pressure to show movement on an underperforming account, and restructuring campaigns produces visible activity immediately. But changes made against a broken signal cannot be evaluated, so you lose the ability to tell whether anything you did worked.

Conversion capture went from 65% to approximately 90% of backend orders.