• 2.6 baseline — 0.6 × season 2.7 (9 gm) + 0.4 × last 10 2.5
• −0.1 opponent leak — they concede 34.1/game vs a 35.7 league average
• −0.5 at this ground — averages 2.1 there (14 gm)
• vs them: averages 1.0 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.