The score says how it ended. xG says how it should have ended: it is the sum of the chances each shot was worth, not an opinion about the game.
Monza created more (1.90 xG against 1.02) and left with nothing.
Monza: −4.7 for the season (16 in the table). Udinese: −1.0 (13). The gap between points and xPTS is built from matches like this one.