• 2.3 baseline — 0.6 × season 1.3 (6 gm) + 0.4 × last 10 3.8
• −0.1 opponent leak — they concede 181.6/game vs a 185.9 league average
• +2.3 at this ground — averages 4.6 there (10 gm)
• vs them: averages 9.0 over 1 game — 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.