• 8.8 baseline — 0.6 × season 8.7 (12 gm) + 0.4 × last 10 9.1
• −1.6 opponent leak — they concede 28.9/game vs a 35.3 league average
• at this ground: too thin to count (1 gm) — shown, adds nothing

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.