• 27.3 baseline — 0.6 × season 27.2 (20 gm) + 0.4 × last 10 27.5
• −0.1 opponent leak — they concede 367.1/game vs a 369 league average
• +1.5 at this ground — averages 28.8 there (51 gm)
• vs them: averages 25.1 over 12 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 3: 10 — far outside his usual range; kept in the average, not smoothed away.