• 4.5 baseline — 0.6 × season 4.8 (6 gm) + 0.4 × last 10 4.0
• −0.8 opponent leak — they concede 28.9/game vs a 35.3 league average
• vs them: averages 0.0 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.