On this week's Huddle Breakdown, @jucojames explained that Celtic have given up more than two xG against in a string of matches against top class opposition over the last season and a bit.
Matches away in AZ Alkmaar, in the Europa League against Real Betis and Bayer 04 Leverkusen, plus this seasons Champions League matches against Real Madrid (Statsbomb) and RB Leipzig have all seen the opponent break the two expected goals mark.
In those seven matches Celtic have conceded 21 goals in total and won once, at home to Real Betis.
I wanted to test this hypothesis further by looking at Champions League matches where at least one of the sides has greater than two xG.
Champion’s League Group Stages 22/23
Using FotMob (which did not have Real Madrid at plus two xG versus Celtic), here are the matches that fit the criteria:

There have been 26 instances in 48 matches of teams achieving over two xG in a single game.
Two of those sides lost despite achieving this benchmark – Barcelona in Munich and Maccabi Haifa in Turin to Juventus.
Out of 24 matches, being on the end of plus two xG resulted in a win on only three occasions.
Athletico Madrid left Porto with a 2-1 victory despite a 1.27 xG difference against.
And to show football has a sense of humour, Athletico Madrid had a 0.86 positive xG difference at home to Club Brugge but lost 0-2.
In a “super club” clash, Barcelona lost 0-2 in Munich despite a 0.32 xG difference.
But on 21/24 occasions, the team with the plus two xG difference won – 88% of the time. There were no draws.
Of those three exceptions, as the xG difference was less that one xG, I would argue only Athletico Madrid’s win in Porto could be classified as “wtf happened there”!
Celtic can hope for that “wtf” moment, but it will be fleeting and not sustainable even over a six-match group campaign.
Brutal
Highlighting that the Champion’s League Group Stage is undoubtedly the most brutal in football, if we consider the averages the situation for the xG concessionists (invented a new word) is bleaker still.
The average xG difference is 1.81 whilst the difference in goal is 2.29.
In other words, teams at this level who generate over two xG against their opponent often go onto score more than just two, as RB Leipzig did to Celtic on Wednesday.
Team such as Bayern Munich and Manchester City will pile on the goals.
You might get plucky as Shakhtar Donetsk did in Madrid. An overwhelming xG difference but a 1-2 defeat.
But more often than not, if you give up xG of two or more, you are getting beaten and possibly getting hammered.
More Depressing Context
In the Scottish league, there have been only 17 instances of plus two xG in 51 matches.
In those matches, three out of 17 have not resulted in a win for the high xG achievers – still an 82% success rate though.
The average xG difference in such matches is 2.31 but the end goal difference is 2.59.
So, in both Scotland and Europe, giving up plus two xG is a BAD thing.
It is worse in Europe, however, as elite sides are more ruthless and more likely to rack up more than two goals off two plus xG.
Conclusion
Whilst Ange Postecoglou has undoubtedly given Celtic more attacking threat against even elite sides, his team continue to give up more than two xG in European ties against “quality” opposition.
This will lead to consistent defeat and occasional hammerings.
As also discussed on the Huddle Breakdown, the defensive shape, alignment and pressing triggers/responses, all need to improve to reduce this risk.