• 4.4 baseline — 0.6 × season 4.2 (19 gm) + 0.4 × last 10 4.8
• +0.4 opponent leak — they concede 101.3/game vs a 93.4 league average
• +1.8 at this ground — averages 6.3 there (82 gm)
• vs them: averages 6.1 over 11 games — 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 20: 11 — far outside his usual range; kept in the average, not smoothed away.