• 70.9 baseline — 0.6 × season 70.2 (13 gm) + 0.4 × last 10 71.9
• −0.6 opponent leak — they concede 539.6/game vs a 544.6 league average
• −0.1 at this ground — averages 70.8 there (67 gm)
• vs them: averages 67.0 over 6 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 7: 25 — far outside his usual range; kept in the average, not smoothed away.