• 2.5 baseline — 0.6 × season 2.2 (19 gm) + 0.4 × last 10 2.9
• −0.3 opponent leak — they concede 28.6/game vs a 32.7 league average
• +0.5 at this ground — averages 3 there (4 gm)
• vs them: averages 3.9 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 18: 7 — far outside his usual range; kept in the average, not smoothed away.