• 2.1 baseline — 0.6 × season 2.2 (19 gm) + 0.4 × last 10 1.9
• +0.0 opponent leak — they concede 94/game vs a 93.4 league average
• +0.3 at this ground — averages 2.4 there (5 gm)
• vs them: averages 3.3 over 3 games — 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.