• 6.8 baseline — 0.6 × season 6.7 (14 gm) + 0.4 × last 10 6.9
• −0.4 opponent leak — they concede 145.2/game vs a 155.4 league average
• +0.3 at this ground — averages 7.1 there (75 gm)
• vs them: averages 7.2 over 9 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 4: 2 — far outside his usual range; kept in the average, not smoothed away.