Ladder Drift + Meta-Aware Regression: The PTCG AI Battle 2026-06 Findings

Use when: (1) Your agent's LB score drops dramatically week-over-week without code changes, (2) You're tempted to add "meta-aware" bonuses (priority targets, matchup bonuses, deck-type detection) to a strong heuristic, (3) Testing agent variants on small samples (60-80 games) and getting noisy/conflicting results, (4) You see error rates spike when testing against meta decks. Do NOT trigger for standard tabular ML — this is about competition agents where (a) the meta shifts daily, and (b) "improvements" that look good in small tests often regress in production. Key lesson: same code, 200-point LB drift in 48h. Key anti-pattern: +600 target bonus on hypothetical Pokemon → …