• 6.7 baseline — 0.6 × season 6.6 (19 gm) + 0.4 × last 10 6.8
• −0.5 opponent leak — they concede 87/game vs a 93.4 league average
• −3.2 at this ground — averages 3.5 there (4 gm)
• wet forecast: too thin to count (1 gm) — shown, adds nothing
• vs them: averages 3.0 over 4 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.