• 2.2 baseline — 0.6 × season 1.9 (17 gm) + 0.4 × last 10 2.6
• −0.1 opponent leak — they concede 33.9/game vs a 35.7 league average
• −1.4 at this ground — averages 0.8 there (41 gm)
• vs them: averages 1.2 over 6 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: 11 — far outside his usual range; kept in the average, not smoothed away.