• 14.8 baseline — 0.6 × season 14.2 (18 gm) + 0.4 × last 10 15.7
• +0.5 opponent leak — they concede 192.6/game vs a 185.9 league average
• −3.8 at this ground — averages 11 there (5 gm)
• vs them: averages 11.0 over 5 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.