Internal Report
Over two years MUD\WTR shifted its Meta delivery optimization from the standard Website Purchase event to a custom Purchase – New Customer event. This report measures that shift at the ad-set level — month by month — and tests whether it correlates with real CAC (blended DTC + Meta 7-day-click), CPM, CTR, sessions, and purchases. Short version: the shift is dramatic and real; CAC did rise alongside it and Q2'26 sits above prior years — but a messy rollout and heavy Q2 seasonality stop us short of proving cause.
What changed. New Customer optimization went from 0% of spend (it didn't exist) to 96% in Q2 2026. Standard Website Purchase fell from ~98% to ~1%. The switch wasn't a clean cutover: it ramped in Q4 2025, pulled back in Q1 2026, then went all-in from April 2026.
What moved with it. In the window where the mix actually varies (Jun 2025 on), heavier New Customer optimization tracks higher CAC — Meta's own 7-day-click CAC (r = +0.64) and blended DTC CAC (r = +0.47) — and fewer sessions (r = −0.64).
Reading it honestly. Q2 is seasonally your weakest quarter, but that doesn't fully explain this away. On real Meta CAC, Q2'26 ($126) is the highest Q2 of the last three years (Q2'24 $111, Q2'25 $104), and blended Q2'26 ($108) likewise steps above Q2'25 ($94) — so Q2'26 CAC is elevated, not merely seasonal. What keeps this a yellow, not a red: the Q1→Q2 climb in 2026 (+17%) is milder than 2024's (+34%), and the ramp → pullback → all-in path plus a broadly tougher 2026 muddy any clean causal read. With 13 varying months and no holdout, this is co-movement — not proof.
Share of monthly Meta spend by the delivery optimization event each ad set was set to. New Customer optimization didn't exist before mid-2025; by spring 2026 it's nearly the entire account. The choppy path — ramp, pullback, all-in — suggests the team was testing rather than flipping a switch.
The same New Customer band as above (purple), now with two CAC lines on top, each from the source you actually trust. Blended CAC is the Daily Stand's Total Blended CAC (DTC) — all DTC marketing spend ÷ Shopify new customers. Meta CAC is pulled straight from the Meta platform on a 7-day-click window — Meta spend ÷ Meta-reported purchases. Read it as "do the lines bend when the band bends?"
Blended CAC starts Jun 2024 — the Daily Stand's monthly tabs don't go back before that (no May 2024 or earlier).
In the active window, both lines climb with New Customer adoption — Meta's own 7-day-click CAC tracks it a bit more tightly (moderate +, r≈0.64) than blended DTC CAC (moderate +, r≈0.47). Meta CAC ran ~$87 in mid-2025 and reached ~$146 by Jun 2026; blended DTC ran ~$88 → $130 over the same window. Read it carefully, though: the all-in landed in Q2 2026, historically your weakest quarter, so some of this is season. But season doesn't fully cover it — §03 shows Q2'26 Meta CAC ($126) is the highest Q2 of the three years. What holds it back from proof: the Q1→Q2 climb itself isn't unusually steep, and the messy ramp → pullback → all-in path can't be untangled from creative and scaling. The switch and rising CAC clearly move together; a holdout (§05) is the only way to call it causal.
Each panel is a single metric over the full window. The purple band behind every chart is New Customer % of spend — so you can eyeball whether a metric bends when the optimization mix bends. Read these as "does the line track the band?", not as proof of cause.
CTR and CPM were already trending up through 2024–25 (cheaper, Reels-heavy clicks) before New Customer optimization existed — so their full-period correlation with the shift is largely coincidental timing, not causation. CAC and sessions are the panels that bend most around the 2026 all-in.
The honest test. Because New Customer % is ~0 for the whole first half of the timeline, it doubles as a "are we in 2026 yet?" variable — anything seasonal will correlate with it by accident. Comparing the same quarter across years strips season out. If New Customer optimization were inflating CAC, Q2'26 (96% NC) should stand out against Q2'24 and Q2'25 (both 0% NC). On real Meta 7-day-click CAC, it does — Q2'26 ($126) is the highest Q2 of the three years. The caveat that keeps this short of a smoking gun: the Q1→Q2 climb in 2026 is actually milder than 2024's (see note below).
Q1→Q2 Meta CAC change: +34% (2024) · +11% (2025) · +17% (2026). Q2 is always softer than Q1, and 2026's Q1→Q2 rise is not unusually steep — 2024's was bigger. So the elevated Q2'26 level is real, but the rate of quarter-over-quarter deterioration doesn't single out the New Customer switch as the culprit.
Pearson correlation between New Customer % and each metric. The full-period column spans all 30 months; the active-period column uses only the months where the mix actually varies (Jun 2025 on). Trust the active column: the full period is dominated by unrelated two-year trends, so a metric like CTR looks correlated there purely because both drifted up over time. Both CAC measures land at a genuine moderate positive in the active window.
|r| < 0.3 ≈ negligible · 0.3–0.5 ≈ weak/moderate · > 0.5 ≈ moderate/strong. None of these establish causation — they're 13–30 monthly points with heavy confounding (seasonality, creative refreshes, budget scaling, and immature attribution on the most recent weeks). Blended CAC uses 25 months (starts Jun 2024); everything else uses 30.
Run a geo or budget-split holdout: a matched set of campaigns on Website Purchase vs Purchase – New Customer for 4–6 weeks, judged on blended new-customer CAC (Daily Spend Tracker ÷ Shopify new customers), not Meta-reported purchases. That's the only way to separate the optimization choice from season, creative, and attribution noise. I can spec it.