• 5.0 baseline — 0.6 × season 4.9 (12 gm) + 0.4 × last 10 5.0
• −0.3 opponent leak — they concede 200.8/game vs a 213.6 league average
• at this ground: too thin to count (2 gm) — shown, adds nothing
• vs them: averages 4.5 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.