• 4.1 baseline — his last 10 games; only 1 this season, too few to blend
• +0.3 opponent leak — they concede 166.4/game vs a 155.4 league average
• +1.6 at this ground — averages 5.7 there (39 gm)
• +1.2 wet forecast — averages 5.3 in the wet (10 gm)
• vs them: averages 5.2 over 6 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.