• 5.7 baseline — 0.6 × season 5.7 (7 gm) + 0.4 × last 10 5.8
• +0.3 opponent leak — they concede 386.5/game vs a 369 league average
• +1.4 at this ground — averages 7.2 there (6 gm)
• vs them: averages 8.0 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.