• 7.7 baseline — 0.6 × season 7.6 (20 gm) + 0.4 × last 10 7.8
• −0.2 opponent leak — they concede 207.8/game vs a 213.6 league average
• −0.9 at this ground — averages 6.8 there (32 gm)
• vs them: averages 8.0 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 20: 14 — far outside his usual range; kept in the average, not smoothed away.