• 7.3 baseline — 0.6 × season 6.3 (4 gm) + 0.4 × last 10 8.8
• +0.0 opponent leak — they concede 369.9/game vs a 369 league average
• +4.6 at this ground — averages 11.9 there (10 gm)
• vs them: averages 11.8 over 10 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.