• 14.4 baseline — 0.6 × season 14.5 (13 gm) + 0.4 × last 10 14.3
• +1.9 opponent leak — they concede 39.8/game vs a 35.3 league average
• −3.2 at this ground — averages 11.2 there (14 gm)
• vs them: averages 12.8 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.