• 28.7 baseline — 0.6 × season 28.9 (21 gm) + 0.4 × last 10 28.5
• +2.0 opponent leak — they concede 368.1/game vs a 344.7 league average
• −2.3 at this ground — averages 26.4 there (24 gm)
• vs them: averages 27.3 over 7 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: 44 — far outside his usual range; kept in the average, not smoothed away.