• 1.7 baseline — 0.6 × season 1.8 (17 gm) + 0.4 × last 10 1.6
• −0.1 opponent leak — they concede 11.8/game vs a 12.2 league average
• −0.2 at this ground — averages 1.5 there (44 gm)
• vs them: averages 1.0 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 6: 5 — far outside his usual range; kept in the average, not smoothed away.