• 12.4 baseline — 0.6 × season 12.3 (20 gm) + 0.4 × last 10 12.6
• −1.0 opponent leak — they concede 21.9/game vs a 23.7 league average
• at this ground: too thin to count (3 gm) — shown, adds nothing
• vs them: averages 7.7 over 6 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.