• 86.4 baseline — 0.6 × season 85.0 (13 gm) + 0.4 × last 10 88.6
• +1.5 opponent leak — they concede 1715.2/game vs a 1686.6 league average
• −10.4 at this ground — averages 76 there (5 gm)
• −7.2 wet forecast — averages 79.3 in the wet (7 gm)
• vs them: averages 80.7 over 9 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 11: 131 — far outside his usual range; kept in the average, not smoothed away.