• 3.9 baseline — his last 10 games; only 2 this season, too few to blend
• −0.4 opponent leak — they concede 83/game vs a 93.4 league average
• +1.4 at this ground — averages 5.3 there (4 gm)
• vs them: averages 4.4 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.