• 10.5 baseline — 0.6 × season 10.6 (19 gm) + 0.4 × last 10 10.2
• +0.5 opponent leak — they concede 386.5/game vs a 369 league average
• −0.1 at this ground — averages 10.3 there (31 gm)
• vs them: averages 12.9 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 6: 20 — far outside his usual range; kept in the average, not smoothed away.