Maybe from all people in this game only you can speak for this.You have squad with stars for 8 lvl but quality for 3 so is normal for your Japanese version of Man.City to loose in cup.I feel really sorry for you,nothing personal.
I support people who speak about Injuries,transfers between servers,rewards from all tournaments and time between the two games.
1.All teams here is like Arsenal with a lot of injured players.
2.Some can get 5* stars players,some have only 3* in tm,some can make transfers in negolation some cant,let the game be one for all.
3.After 10 lvl money from tournaments is not enough for new transfers and stadium upgrade.
4.If i have 2 game away in 15 min i cant change time,i cant make subs, i cant heal my players.I think that not many used change time service so make sure that there is always at least one hour between at least two games.