My main concern now is that the team avoids the 3rd season burnout that has clearly done City over. Klopp's managed fitness and injuries very well, but fatigue is inevitable and transfers will be limited. It's right to be concerned, but it's equally fine to trust that the manager, club and owners have the situation in hand. After all, the got us here. 
I think burnout is only part of why they've dropped off, and even burnout is hard to believe with a squad that is so deep and expensive. There's no doubt that sustaining those levels over multiple seasons is hard, but two other factors have also played a part.
Firstly, teams finally started having a go at City after 2 years of rolling over and getting dicked. Kompany left, Laporte got injured, and suddenly they were vulnerable and everyone smelt blood. Their aura had gone, and the midfield and attack that were used to dominating possession suddenly had to track back and help as Fernandinho was no longer there to break up the counter. They were still able to crush teams, but have suffered 8 defeats in 31 games after only losing 4 across the previous 2 seasons. It's the most defeats Guardiola has suffered in a season, and we could make it worse on Thursday.
Secondly - and this is where the burnout might come in, but more a psychological than physical one - they probably weren't expecting us to be able to sustain the levels of last season given our squad depth. When we not only sustained it but went up another level, they collectively shit themselves as they had no more levels left to improve. They are not as mentally strong as us, and that includes the manager who had several rants at officials and the media (and the sky
), which no doubt rubs off on the players. Klopp gets passionate but never makes excuses, never blames anyone, and is always positive and humble in defeat.
If you looks at individual stats, City players all played less games and ran less minutes than us, and were able to rotate far more often. They had a piss easy CL group and easy runs in the domestic cups again so they can't blame that either. Arguably the league wasn't any harder this year either as no-one else (except us) improved significantly over last season - Wolves and Sheffield Utd perhaps, but they simply replaced Spurs and Arsenal...
Whilst there's every chance other teams close that gap next season, there's also every chance they don't. City's core players that helped their success in the last 10 years are fading or leaving, and as this season has shown - when their leaders aren't on the pitch or don't step up, they crumble (sounds familiar...). Their transfer hit rate is nowhere near ours, and despite all the accolades Guardiola receives about his coaching, its worth noting he's spent over £1bn in 12 years. Utd are still turning their perennial corner, and when pundits praise their 14-game unbeaten run (dating back to February, which is basically about a month ago...), its obvious how far they've fallen. Arsenal and Spurs are all over the place, Leicester lack consistency, and Chelsea have a great squad but it remains to be seen whether Lampard knows how to use it properly.
The future is very bright, and if there's a risk of us having burnout then it will be interesting to see how physically and mentally exhausted others will get trying to catch up - especially as the weight of chasing number 19 has now been lifted.
