Here is some tips for you so that you can definitely say that your team is suffering form issues, this is called "dark period"
Top 5 You can actually see all your players wiped out of the Top 5 list, here is my Top 5 before and after...
Lousy match results In a match where you supposed to bury them 10+ goals, you did win just 3-1 or something like that, check your past match results and ratings, the player who never get MOTM before will be awarded MOTM.
Morale Player morale will constantly drop during the dark period, as I think that something about love must take their form down. Eventually if your player is on high morale then they can still perform lousy performances.
Before
After
Remember that the dark period only last for 3-4 days, and it will end very soon, just like in Season 2 of my team, they performing very bad (Matchday 16-20) then they managed a 5-1 comeback in the CL on Saturday, then I'm on "big winning" form...