• 4.4 baseline — 0.6 × season 4.4 (14 gm) + 0.4 × last 10 4.4
• +0.1 opponent leak — they concede 12.5/game vs a 12.2 league average
• −1.7 at this ground — averages 2.7 there (46 gm)
• vs them: averages 1.0 over 7 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.