• 9.1 baseline — 0.6 × season 10.4 (5 gm) + 0.4 × last 10 7.2
• +2.4 opponent leak — they concede 44.8/game vs a 35.3 league average
• −1.2 at this ground — averages 7.9 there (17 gm)
• vs them: averages 9.0 over 1 game — 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 5: 23 — far outside his usual range; kept in the average, not smoothed away.