• 170.8 baseline — 0.6 × season 174.3 (20 gm) + 0.4 × last 10 165.7
• +12.4 opponent leak — they concede 1810.8/game vs a 1687.8 league average
• at this ground: too thin to count (1 gm) — shown, adds nothing
• vs them: averages 184.0 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.