• 9.1 baseline — 0.6 × season 9.8 (6 gm) + 0.4 × last 10 7.9
• −0.1 opponent leak — they concede 211.2/game vs a 213.6 league average
• +1.5 at this ground — averages 10.6 there (5 gm)

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 2: 17 — far outside his usual range; kept in the average, not smoothed away.