• 31.7 baseline — 0.6 × season 31.6 (17 gm) + 0.4 × last 10 31.9
• +2.9 opponent leak — they concede 594.5/game vs a 544.2 league average
• +15.8 at this ground — averages 47.5 there (4 gm)
• vs them: averages 32.7 over 3 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 23: 73 — far outside his usual range; kept in the average, not smoothed away.