• 0.2 baseline — his last 10 games; only 2 this season, too few to blend
• +0.0 opponent leak — they concede 12.8/game vs a 12.8 league average
• +0.4 at this ground — averages 0.6 there (41 gm)
• vs them: averages 0.8 over 4 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.