• 31.2 baseline — 0.6 × season 30.6 (7 gm) + 0.4 × last 10 32.2
• +1.9 opponent leak — they concede 365.4/game vs a 344.9 league average
• −4.8 at this ground — averages 26.5 there (54 gm)
• vs them: averages 23.9 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 1: 13 — far outside his usual range; kept in the average, not smoothed away.