• 14.2 baseline — 0.6 × season 14.5 (11 gm) + 0.4 × last 10 13.8
• −0.1 opponent leak — they concede 365.8/game vs a 369 league average
• +7.6 wet forecast — averages 21.8 in the wet (6 gm)
• vs them: averages 18.4 over 8 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.