• 1.9 baseline — 0.6 × season 2.2 (19 gm) + 0.4 × last 10 1.5
• +0.0 opponent leak — they concede 155.9/game vs a 155.4 league average
• +0.7 at this ground — averages 2.7 there (18 gm)
• vs them: averages 4.5 over 2 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.