• 3.6 baseline — 0.6 × season 3.5 (8 gm) + 0.4 × last 10 3.7
• −0.3 opponent leak — they concede 32.7/game vs a 35.7 league average
• −0.2 at this ground — averages 3.4 there (49 gm)
• vs them: averages 2.2 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.