• 2.9 baseline — 0.6 × season 2.9 (20 gm) + 0.4 × last 10 3.0
• −0.1 opponent leak — they concede 31.7/game vs a 32.8 league average
• +0.3 at this ground — averages 3.3 there (53 gm)
• vs them: averages 2.7 over 9 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 10: 8 — far outside his usual range; kept in the average, not smoothed away.