• 10.3 baseline — 0.6 × season 9.6 (20 gm) + 0.4 × last 10 11.3
• +0.3 opponent leak — they concede 160.7/game vs a 155.4 league average
• −2.6 at this ground — averages 7.6 there (47 gm)
• vs them: averages 6.1 over 7 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 19: 20 — far outside his usual range; kept in the average, not smoothed away.