We ran a structural rebuild sprint across every active Performance Max account on the paid-media practice between July and August. This is the wrap-up note on what we did, what changed, and what partners should monitor in Q4.
Why we ran the sprint: Google shipped two meaningful Performance Max updates earlier in 2025 that changed how the algorithm interprets asset groups, search themes, and brand-traffic exclusions. The updates were not announced as breaking changes but they were. Accounts that were performing well in May were drifting by July, and the drift was happening for structural reasons, not for the optimization-tweak reasons that monthly check-ins normally surface.
What we rebuilt, per account: brand-traffic exclusion lists got moved from the campaign level to the account level so PMax cannot use brand search to inflate apparent ROAS. Asset groups got consolidated where the data showed fragmentation was hurting the algorithm's learning rather than helping it. Search themes got pruned where we found them either redundant with the headline-derived themes Google generates automatically or actively conflicting. None of these are exotic changes. They are the things you do when the platform shifts.
Every rebuilt account got a written rationale memo from the senior buyer. The memo walked through what changed in the platform, what we did on the account, why we did it, and what the partner should expect over the following 30 to 60 days. Partners reviewed and signed off before any changes shipped. The point of the written rationale is that account managers should be able to read the memo and explain the work on a client call without being the buyer themselves.
Results across rebuilt accounts: median 18 percent reduction in cost-per-acquisition over the trailing 60-day window, compared to the 30 days preceding the rebuild. Spread was wide. The best account saw a 41 percent CAC reduction. Two accounts moved against us in the first 30 days and then recovered. One account stayed flat. The recoveries took 6 to 8 weeks, which is typical for PMax restructuring at scale.
What partners should monitor in Q4: PMax accounts that have been restructured need a re-baseline conversation around month three, not month one. The first month's numbers will fluctuate as the algorithm relearns. We will surface the re-baseline in October and November monthly reports. If you have specific questions ahead of those, your buyer is briefed.