• 27.7 baseline — 0.6 × season 27.5 (19 gm) + 0.4 × last 10 28.0
• −0.2 opponent leak — they concede 365.8/game vs a 369 league average
• at this ground: too thin to count (1 gm) — shown, adds nothing
• −4.2 wet forecast — averages 23.5 in the wet (6 gm)
• vs them: averages 27.5 over 8 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. Round 15: 43 — far outside his usual range; kept in the average, not smoothed away.