• 9.6 baseline — 0.6 × season 9.6 (7 gm) + 0.4 × last 7 9.6
• +0.2 opponent leak — they concede 378.4/game vs a 369 league average
• at this ground: too thin to count (1 gm) — shown, adds nothing
• vs them: averages 20.0 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. Round 2: 20 — far outside his usual range; kept in the average, not smoothed away.