• 13.3 baseline — 0.6 × season 13.6 (7 gm) + 0.4 × last 10 12.8
• −0.2 opponent leak — they concede 364.1/game vs a 369 league average
• −2.7 at this ground — averages 10.6 there (12 gm)
• vs them: averages 10.4 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 23: 6 — far outside his usual range; kept in the average, not smoothed away.