• 33.2 baseline — 0.6 × season 33.1 (18 gm) + 0.4 × last 10 33.4
• +0.1 opponent leak — they concede 345.7/game vs a 344.9 league average
• −0.2 at this ground — averages 33 there (5 gm)
• −5.2 wet forecast — averages 28 in the wet (5 gm)
• vs them: averages 35.0 over 8 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.