• 2.7 baseline — 0.6 × season 3.0 (14 gm) + 0.4 × last 10 2.3
• +0.2 opponent leak — they concede 164.6/game vs a 155.4 league average
• +1.0 at this ground — averages 3.7 there (88 gm)
• vs them: averages 4.0 over 6 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.