• 2.7 baseline — 0.6 × season 2.1 (20 gm) + 0.4 × last 10 3.6
• −0.5 opponent leak — they concede 19.7/game vs a 23.7 league average
• +0.8 at this ground — averages 3.5 there (17 gm)
• vs them: averages 2.8 over 5 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 13: 12 — far outside his usual range; kept in the average, not smoothed away. Round 18: 12 — far outside his usual range; kept in the average, not smoothed away.