• 62.3 baseline — 0.6 × season 59.4 (17 gm) + 0.4 × last 10 66.6
• −4.8 opponent leak — they concede 503.2/game vs a 545.7 league average
• at this ground: too thin to count (2 gm) — shown, adds nothing
• vs them: averages 40.9 over 7 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.