Same Month, Different Year — Why June 2025 and June 2026 Told Opposite Stories
Same Month, Different Year — Why June 2025 and June 2026 Told Opposite Stories
> Signal Syndicate Research Library · Season Reviews · Educational intelligence · Not betting advice
Regime is a fancy word for a simple idea: the game changed. The same model label on the same calendar month can win in one year and lose in the next — because players, books, and run environments moved.
This educational review walks through our K-props shadow autopsy where June flipped between 2025 and 2026, and what we did about it. The decision it led to — retiring the lane outright — is written up in why we retired K-props.
The headline contrast (historical estimates)
| Window | Sample | ROI (est.) | How to read it |
|---|---|---|---|
| **Jun 2025** shadow | ~3 bets | ~**+27%** | Tiny n — hypothesis only |
| **Jun 2026** shadow | 20 bets | ~**−14%** | Denser — forward stress test |
| **May–Jul 2026 full** | 34 bets | ~**−10%** | Retirement review window |
June is the same on the calendar. The market year was not.
What "regime" means here (plain English)
We are not claiming a mystical June curse. We are saying:
- Strike density and book limits moved after we densified slates (Phase 66)
- Under vs over splits diverged (~−20% under vs ~−5% over on June 2026 split shown in autopsy)
- Prior-year replication failed — a core promotion requirement at Signal
That pattern triggers monitor or retire — not "pull more data until green."
NBA parallel (why this doc links to regime seasonality)
MLB June flip is props-specific, but the lesson generalizes. Our NBA totals lane shows a similar seasonal split in honest holdouts: stronger Oct–Dec windows vs weaker Jan–Apr forward periods on the same model skeleton.
We publish both — see the NBA regime research thread and the `nba-regime-seasonality` reel narrative. Seasonality is not a ship signal. It is a risk label.
What we did next
1. Shadow-only logging until sample and court cleared
2. Credit gate STOP on further K-prop densification pulls
3. RETIRE verdict on May–Jul K lane after expanded review
4. Library publish so Ask Signal can answer regime questions with citations
Takeaway for bettors and creators
- Do not extrapolate one hot month into a product.
- Do ask whether a platform tests the same calendar window across years.
- Do treat small-n wins as stories, not subscriptions.
Ask Signal: "Why did June results flip year over year?" or "What is regime in sports betting models?"
Research only · estimates only · not betting advice · past results do not predict future performance.