• 3.6 baseline — 0.6 × season 3.6 (10 gm) + 0.4 × last 10 3.6
• −0.4 opponent leak — they concede 82.1/game vs a 93.4 league average
• +0.5 at this ground — averages 4.1 there (7 gm)
• vs them: averages 5.0 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 9: 9 — far outside his usual range; kept in the average, not smoothed away.