from 5.1 baseline, −0.8 at this ground

• 5.1 baseline — 0.6 × season 4.4 (7 gm) + 0.4 × last 10 6.0
• +0.0 opponent leak — they concede 156.8/game vs a 155.3 league average
• −0.8 at this ground — averages 5.8 there against his own 6.8 in those same seasons — 85% of his own level (12 gm)
• vs them: averages 6.9 over 8 games — 106% of his own level in those seasons — 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.