• 1.3 baseline — 0.6 × season 1.3 (6 gm) + 0.4 × last 6 1.3
• +0.2 opponent leak — they concede 26.7/game vs a 23.7 league average
• at this ground: too thin to count (2 gm) — shown, adds nothing
• vs them: averages 0.0 over 1 game — 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.