• 5.2 baseline — 0.6 × season 5.1 (13 gm) + 0.4 × last 10 5.3
• +0.3 opponent leak — they concede 164/game vs a 155.4 league average
• +0.5 at this ground — averages 5.7 there (28 gm)
• vs them: averages 5.4 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.