• 4.3 baseline — 0.6 × season 4.0 (4 gm) + 0.4 × last 10 4.8
• +0.0 opponent leak — they concede 213.7/game vs a 213.6 league average
• +2.3 at this ground — averages 6.6 there (7 gm)
• vs them: averages 12.0 over 1 game — 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.