• 2.0 baseline — 0.6 × season 1.9 (20 gm) + 0.4 × last 10 2.1
• +0.3 opponent leak — they concede 64.2/game vs a 56.6 league average
• −0.7 at this ground — averages 1.3 there (4 gm)
• +1.9 wet forecast — averages 3.8 in the wet (12 gm)
• vs them: averages 2.1 over 7 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.