• 4.2 baseline — 0.6 × season 4.9 (16 gm) + 0.4 × last 10 3.3
• −0.2 opponent leak — they concede 31.4/game vs a 32.8 league average
• +0.9 at this ground — averages 5.2 there (6 gm)
• vs them: averages 6.4 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 7: 16 — far outside his usual range; kept in the average, not smoothed away.