• 8.8 baseline — 0.6 × season 8.4 (14 gm) + 0.4 × last 10 9.4
• −0.5 opponent leak — they concede 201.8/game vs a 213.6 league average
• at this ground: too thin to count (2 gm) — shown, adds nothing
• vs them: averages 10.0 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.