• 3.7 baseline — 0.6 × season 4.2 (6 gm) + 0.4 × last 10 3.1
• +1.0 opponent leak — they concede 117.8/game vs a 93.4 league average
• −1.7 at this ground — averages 2 there (11 gm)
• vs them: averages 1.0 over 2 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: 9 — far outside his usual range; kept in the average, not smoothed away.