• 15.7 baseline — 0.6 × season 15.3 (15 gm) + 0.4 × last 10 16.3
• −0.9 opponent leak — they concede 175.7/game vs a 185.9 league average
• +0.3 at this ground — averages 16 there (45 gm)
• vs them: averages 13.8 over 4 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 14: 28 — far outside his usual range; kept in the average, not smoothed away.