Methodology

1. Data sources

Each live game pulls catalog + market prices from its public/licensed feed: Scryfall (MTG), Pokémon TCG API (PKM), YGOPRODeck (YGO). Snapshots land in price_snapshotsas USD-denominated fields. Buy links may still open TCGPlayer / Cardmarket product pages; that is separate from any developer API (TCGPlayer's is closed to new applicants).

2. Catalog value proxy

Sum of card snapshot prices on a day for cards priced ≥ $0.5. This is a basket / index proxy — not transaction volume, not market capitalisation, not verified sales. A capped variant uses min(price, $250) per card so a single high outlier cannot dominate the sum.

3. Equal-weight index

• For cards with valid prices on day t and a prior day: r_i = (p_t − p_prior) / p_prior
• Daily return R = mean(r_i) (equal weight — expensive cards do not dominate).
• Index starts at 100 on the first day; later Index_t = Index_prior × (1 + R).
• Momentum score centres a flat market near 50: clip(50 + 50·tanh(R / 0.05)).

Rollups are stored in daily_game_metrics so pages do not scan millions of snapshot rows per request.

4. Opportunity scoring (v2)

• Price move vs prior snapshot in the selected window (d1 / d7 / d30).
• Relative-to-game: card % move minus that game's median % move.
• Undervalued vs recent mean when enough history points exist.
• Consistency bonus when a shorter window agrees on direction.
• Liquidity / volume proxy = |% move| × price-tier weight — not sales.
• Confidence = data-quality coverage (history points, tier, relative context) in [0, 1] — not an outcome probability.

5. Track record lifecycle

High-score opportunities are logged idempotently into intel_signals (unique on card + period + entry date + signal version). After 30 calendar days, we resolve with the first priced snapshot on/after the horizon date. Public pages show pending/resolved counts and individual outcomes only when rows exist. We do not publish hit-rate percentages until the resolved sample is meaningful — and we always state the sample size.

6. Shop disclosure

TCG Bros operates a UK shop. Opportunity cards may link to marketplace buy destinations and our shop search. Rankings are computed from snapshot math and cannot be paid or manually moved.

What we do not claim

No verified sales bars, no 14-game coverage, no guaranteed ROI, no financial advice, no fabricated history when only one snapshot day exists.