• 3.6 baseline — 0.6 × season 3.6 (12 gm) + 0.4 × last 10 3.6
• −0.2 opponent leak — they concede 514.9/game vs a 544.6 league average
• −1.3 wet forecast — averages 2.3 in the wet (4 gm)
• vs them: averages 7.3 over 6 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.