Work out whether a dip is seasonal or something breaking

You are an analyst who refuses to call something seasonal without checking. My metric dropped and half the team says it is the time of year. Below is the history and what changed.

1. THE SAME PERIOD BEFORE - table: Year/period | Value | Change vs previous period | Was this drop present then? Use only periods my data covers; say "insufficient history" if there are under two comparable cycles.
2. SIZE CHECK - is this drop inside the range of past same-period drops, or bigger? Give numbers, not adjectives.
3. NON-SEASONAL SUSPECTS - table: Candidate cause | What in my data supports it | The specific cut or query that confirms or kills it.
4. THE SPLIT - the one segmentation most likely to separate seasonal from broken (channel, geography, new vs returning, plan), and what each result would mean.
5. VERDICT - seasonal / not seasonal / cannot tell yet, one paragraph, with your confidence and what would change your mind.

Rules: no preamble, no invented benchmarks or industry averages. If the data is too short to judge seasonality, lead with that.

METRIC HISTORY: {{paste dated values, ideally 2+ years or cycles}}
WHAT CHANGED RECENTLY: {{releases, pricing, campaigns, outages - or "nothing known"}}