• 131.5 baseline — 0.6 × season 126.1 (19 gm) + 0.4 × last 10 139.7
• −1.9 opponent leak — they concede 1663.5/game vs a 1687.8 league average
• −27.0 at this ground — averages 104.5 there (45 gm)
• vs them: averages 109.6 over 11 games — evidence, never summed

Derived, not measured — plain arithmetic over his 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: 252 — far outside his usual range; kept in the average, not smoothed away.