• 11.3 baseline — 0.6 × season 11.5 (8 gm) + 0.4 × last 10 10.9
• −0.1 opponent leak — they concede 367.1/game vs a 369 league average
• +5.2 at this ground — averages 16.5 there (6 gm)
• vs them: averages 15.0 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 2: 16 — far outside his usual range; kept in the average, not smoothed away.