• 13.6 baseline — his last 10 games; only 2 this season, too few to blend
• −0.6 opponent leak — they concede 353.4/game vs a 369 league average
• −2.3 at this ground — averages 11.3 there (6 gm)
• vs them: averages 23.0 over 1 game — 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.