• 2.3 baseline — 0.6 × season 2.3 (6 gm) + 0.4 × last 10 2.2
• +0.1 opponent leak — they concede 164.6/game vs a 155.4 league average
• +1.5 at this ground — averages 3.8 there (10 gm)
• vs them: averages 4.0 over 10 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.