• 59.2 baseline — 0.6 × season 59.6 (13 gm) + 0.4 × last 10 58.7
• +4.3 opponent leak — they concede 1810.8/game vs a 1687.8 league average
• at this ground: too thin to count (3 gm) — shown, adds nothing
• vs them: averages 37.3 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.