• 0.1 baseline — his last 10 games; only 2 this season, too few to blend
• −0.0 opponent leak — they concede 8.1/game vs a 9.7 league average
• +0.5 at this ground — averages 0.6 there (5 gm)
• vs them: averages 0.4 over 5 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.