• 2.0 baseline — 0.6 × season 1.8 (19 gm) + 0.4 × last 10 2.3
• +0.0 opponent leak — they concede 57/game vs a 56.6 league average
• +0.5 wet forecast — averages 2.5 in the wet (4 gm)
• vs them: averages 1.0 over 4 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.