• 1.9 baseline — 0.6 × season 1.8 (15 gm) + 0.4 × last 10 2.1
• −0.1 opponent leak — they concede 33.9/game vs a 35.7 league average
• +2.6 at this ground — averages 4.5 there (51 gm)
• vs them: averages 4.4 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 13: 7 — far outside his usual range; kept in the average, not smoothed away.