• 10.3 baseline — 0.6 × season 10.6 (12 gm) + 0.4 × last 10 9.9
• −0.3 opponent leak — they concede 357.8/game vs a 369 league average
• −0.6 at this ground — averages 9.7 there (9 gm)
• vs them: averages 9.5 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. Round 1: 20 — far outside his usual range; kept in the average, not smoothed away.