• 10.1 baseline — 0.6 × season 9.8 (20 gm) + 0.4 × last 10 10.5
• +0.9 opponent leak — they concede 233.1/game vs a 213.6 league average
• −2.4 at this ground — averages 7.7 there (18 gm)
• wet forecast: too thin to count (3 gm) — shown, adds nothing
• vs them: averages 8.0 over 2 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.