• 5.2 baseline — 0.6 × season 5.0 (20 gm) + 0.4 × last 10 5.6
• +0.3 opponent leak — they concede 164/game vs a 155.4 league average
• −1.1 at this ground — averages 4.2 there (68 gm)
• vs them: averages 5.0 over 9 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 21: 12 — far outside his usual range; kept in the average, not smoothed away.