• 10.4 baseline — his last 10 games; only 2 this season, too few to blend
• +0.3 opponent leak — they concede 190.8/game vs a 185.9 league average
• −4.4 at this ground — averages 6 there (12 gm)
• +3.3 wet forecast — averages 13.8 in the wet (4 gm)
• vs them: averages 9.3 over 3 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.