• 13.5 baseline — 0.6 × season 13.8 (6 gm) + 0.4 × last 9 12.9
• +0.0 opponent leak — they concede 369.9/game vs a 369 league average
• at this ground: 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.