• 13.9 baseline — 0.6 × season 14.0 (19 gm) + 0.4 × last 10 13.8
• +0.6 opponent leak — they concede 386.2/game vs a 369 league average
• −0.3 at this ground — averages 13.6 there (14 gm)
• vs them: averages 23.0 over 1 game — 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: 3 — far outside his usual range; kept in the average, not smoothed away.