• 35.9 baseline — 0.6 × season 35.4 (18 gm) + 0.4 × last 10 36.6
• +0.5 opponent leak — they concede 552.1/game vs a 544.6 league average
• +2.8 at this ground — averages 38.8 there (4 gm)
• +7.0 wet forecast — averages 42.9 in the wet (10 gm)
• vs them: averages 39.4 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.