from 82.2 baseline, −2.2 at this ground

• 82.2 baseline — 0.6 × season 80.3 (23 gm) + 0.4 × last 10 85.0
• +0.6 opponent leak — they concede 546.9/game vs a 543.1 league average
• −2.2 at this ground — averages 57.9 there against the player's own 59.4 in those same seasons — 97% of that level (52 gm)
• vs them: averages 69.5 over 6 games — 119% of the player's own level in those seasons — evidence, never summed

Derived, not measured — plain arithmetic over real games, shown in full. Adjustments can overlap (a game at this ground can also be a wet one); they add simply, and this note is the admission. Round 12: 126 — far outside the usual range; kept in the average, not smoothed away.