• 14.2 baseline — 0.6 × season 15.2 (20 gm) + 0.4 × last 10 12.7
• +0.4 opponent leak — they concede 378.4/game vs a 369 league average
• +1.5 at this ground — averages 15.7 there (6 gm)
• vs them: averages 17.2 over 5 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 6: 25 — far outside his usual range; kept in the average, not smoothed away.