• 9.4 baseline — 0.6 × season 9.9 (20 gm) + 0.4 × last 10 8.7
• +1.3 opponent leak — they concede 106.2/game vs a 93.4 league average
• −1.7 at this ground — averages 7.7 there (17 gm)
• vs them: averages 7.7 over 13 games — evidence, never summed

Most signals here point under while you're on the over — worth reading the working above before you commit.

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.