• 1.8 baseline — 0.6 × season 1.7 (13 gm) + 0.4 × last 10 2.0
• +0.1 opponent leak — they concede 368.1/game vs a 344.9 league average
• +1.0 at this ground — averages 2.8 there (6 gm)
• vs them: averages 3.1 over 10 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.