• 5.5 baseline — 0.6 × season 5.7 (19 gm) + 0.4 × last 10 5.2
• +1.4 opponent leak — they concede 117.8/game vs a 93.4 league average
• +0.6 at this ground — averages 6.1 there (21 gm)
• wet forecast: too thin to count (3 gm) — shown, adds nothing
• vs them: averages 6.3 over 3 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.