• 2.0 baseline — 0.6 × season 1.8 (18 gm) + 0.4 × last 10 2.2
• −0.1 opponent leak — they concede 31.4/game vs a 32.7 league average
• −1.2 at this ground — averages 0.8 there (20 gm)
• vs them: averages 1.5 over 4 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 19: 6 — far outside his usual range; kept in the average, not smoothed away.