I'm inclined to agree with him as we haven't performed in Europe, on paper top 5 easily...games aren't won on paper.
Barcelona, Real Madrid, Bayern Munich, Chelsea, Atletico Madrid, Chelsea, PSG, Juventus (1 great season), Dortmund (terrible season last year) have all been better in Europe recently. Add to that there are other clubs in Europe that have had better European Campaigns, like Monaco last year.
I would personally have us level with Chelsea, Atletico and PSG but behind Real, Barca and Bayern. Its time to prove it on the pitch, as long as we avoid Barca in the knockout rounds, I have a good feeling about our European Campaign this year.
Right, here's my opinion on the 9 clubs you mention above.
Barca - undoubtedly the best team in the world.
Real - still ahead of us, but other than Ronaldo I don't see their squad being that much better than us, they are definitely in decline.
Munich - still ahead of us, they just have more experience in big games, we'll catch them soon enough.
Chelsea - they were ahead of us last year by quite a distance, but a poor transfer window for them has shown, we dominated them 3-0, it could have been 5/6 ahead at half time!
Athletico - they have some good technical players and arguably the best manager in the world (despite playing boring football), but they aren't the team they were 2 years ago, to many good players have left - I think we're ahead of them.
Chelsea - they got mentioned twice in your list
PSG - Really good team, I'd say they are 'just' ahead of us because they don't have any domestic competition.
Juventus - absolutely no chance are they ahead of us
now. last season, maybe, but they've lost 3 of their 4 best players and domestic competition has improved.
Dortmund - No Klopp, no champions league football, no Lewandowski - they are no where near the Dortmund of 2013 and arguing they're ahead of us is laughable, there are at least 4 teams ahead of them in Germany alone!
I think a lot of City fans forget that in the last 2 seasons we've been in a group with Bayern and faced Barca in the round of 16. Juventus last year had a group of Athletico, Olympiakos and Malmo (they finished second), they beat the poorest Dortmund team we've seen in half a decade to reach the quarters, where they beat a Monaco side that finished 12 points behind PSG - they qualified for the final after having the game of their lives vs Madrid - then played Barca in the final and got outclassed on every front - and people think they had some incredible team that was miles ahead of ours etc - they didn't they just got lucky one season.