• 12.7 baseline — 0.6 × season 12.9 (16 gm) + 0.4 × last 10 12.3
• −0.8 opponent leak — they concede 345.4/game vs a 369 league average
• +1.4 at this ground — averages 14.1 there (9 gm)
• vs them: averages 15.6 over 11 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 7: 1 — far outside his usual range; kept in the average, not smoothed away.