• 2.3 baseline — 0.6 × season 2.6 (16 gm) + 0.4 × last 10 1.9
• −0.1 opponent leak — they concede 53.8/game vs a 56.6 league average
• +1.3 at this ground — averages 3.7 there (9 gm)
• vs them: averages 3.9 over 11 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 6: 9 — far outside his usual range; kept in the average, not smoothed away.