• 7.9 baseline — 0.6 × season 7.8 (18 gm) + 0.4 × last 10 8.2
• +0.2 opponent leak — they concede 377.9/game vs a 369 league average
• −0.9 at this ground — averages 7.1 there (18 gm)
• vs them: averages 7.0 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.