• 1.7 baseline — 0.6 × season 1.6 (19 gm) + 0.4 × last 10 2.0
• +0.1 opponent leak — they concede 10.2/game vs a 9.7 league average
• −0.2 at this ground — averages 1.5 there (4 gm)
• vs them: averages 1.1 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.