What xG actually tells you (and what it doesn’t)

Expected goals measures the quality of chances, not the quality of a team. A 0.8 xG performance can deserve a win or deserve nothing — the number tells you which shots were taken, not whether they were taken well.

The useful habit is trend-reading. One match’s xG is noise; eight matches of xG consistently above the points total says a side is better than its table, and usually gets corrected upward.

What xG cannot do is measure nerve. Penalties, weather, a nervous debutant defender — the model sees none of it. Treat it as one honest voice among several, never the only one.