Try it and see where that gets you. If you're getting this riled up from an explanation of xG then you must be about 10.
So finishing is a really statistically interesting part of the game, in that you can't find a rhyme of reason to it. We think of some players 'good finishers', but there's little underlying that. A player like Kane will go from overshooting to undershooting his xG season-to-season. Salah, Firmino and Jesus all undershot their xG last season, while Danny Ings massively overshot his. Bamford has gone from undershooting his xG in the EFL by 9 goals last season to overshooting it by 1.5 in the PL this.
A more sound analysis is that if a team is generating good chances and not finishing them this is either due to a. bad luck, which will right itself long term, b. having a game plan that creates a large aggregate xG but few high-xG chances (e.g. taking loads of pot-shots from 30yards) or having chances funneled towards a player who is unsuited to the gameplan or of significantly lower quality from the rest of the team.
Similarly with teams underpforming their xG conceded, this will usually show poor performance from a keeper (e.g. Matt Ryan is having a stinker at Brighton so far) but will also be a luck element if opponents are finishing low-probability chances. There's also a stylistic element to the game - Leeds defend by having the ball and committing men forward to pen the opponent back. However, when that breaks down with men committed forward it will usually result in concession of a high-xG chance.