• 7.7 baseline — 0.6 × season 8.6 (12 gm) + 0.4 × last 10 6.4
• +0.5 opponent leak — they concede 368.1/game vs a 344.9 league average
• +3.1 at this ground — averages 10.8 there (5 gm)
• vs them: averages 28.0 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: 28 — far outside his usual range; kept in the average, not smoothed away.