• 1.4 baseline — 0.6 × season 1.3 (9 gm) + 0.4 × last 10 1.4
• +0.1 opponent leak — they concede 101.3/game vs a 93.4 league average
• +0.4 at this ground — averages 1.8 there (34 gm)
• vs them: averages 1.7 over 3 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.