It was in the past that we do use past record to predict the future, but this season proved everyone wrong that past history doesn't guarantee future results. I see Chelsea as the favorite in this match, because City have lost form and are unpredictable when playing with big clubs. Imagine how they lost their only chance of qualifying to the round of 16 to PSG, despite on two goals lead.
This weekend's match will be very tough for Manchester City because Chelsea are a very different team from last season and what you said is true that this season all teams have experienced a difference in performance, both those who were good before and are now good, and vice versa as we saw together with one team, Manchester City. I also don't think Chelsea will give up easily when playing at Manchester City's home this weekend because Chelsea also really want to maintain their position in the top four zone so they will try their best to win at Manchester City's home.
Yeah this match will be a very difficult for both teams however Manchester city may win the match because they just lost to PSG and will not take chances in this game and since they are at home they will do everything possible to put a smile on the face of there fans, Chelsea are playing very well this few days they won there last game with wolves and may want to continue winning so they can fight for the premier league title or to go to number three in the premier league table but winning Manchester city in there home will be a very difficult one because Manchester City are now a little bit inform and I can say they are equal when it comes to being form, however if they want to win Manchester city they can all they need to do is play very well and also make there defense very strong they have a very good strikers which I believe can score goals for them, but the problem with Chelsea is that they are never consistent they have all it takes to even win the premier league title but they are never consistent, some months ago they where playing very well and i even thought they will win the premier league title this season but they just lost form.
I wish the both teams Goodluck on this game.