• 3.7 baseline — 0.6 × season 3.7 (10 gm) + 0.4 × last 10 3.7
• +0.3 opponent leak — they concede 101.3/game vs a 93.4 league average
• −0.6 at this ground — averages 3.1 there (13 gm)
• vs them: averages 5.0 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 19: 1 — far outside his usual range; kept in the average, not smoothed away.