• 7.4 baseline — 0.6 × season 7.4 (9 gm) + 0.4 × last 10 7.3
• −0.5 opponent leak — they concede 145.2/game vs a 155.4 league average
• −1.0 at this ground — averages 6.4 there (12 gm)
• vs them: averages 9.0 over 8 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: 15 — far outside his usual range; kept in the average, not smoothed away.