• 23.0 baseline — 0.6 × season 22.8 (16 gm) + 0.4 × last 10 23.4
• +0.6 opponent leak — they concede 377.9/game vs a 369 league average
• −3.9 at this ground — averages 19.1 there (56 gm)
• vs them: averages 19.6 over 8 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 17: 10 — far outside his usual range; kept in the average, not smoothed away.