• 13.8 baseline — 0.6 × season 14.4 (18 gm) + 0.4 × last 10 13.0
• −0.4 opponent leak — they concede 357.8/game vs a 369 league average
• wet forecast: too thin to count (2 gm) — shown, adds nothing

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.