Many factors aye, like every other match in reality players suffer broken ankles, toes, legs ... I think not. Factors like 3 players getting injured in simple league matches when the manager has instructed them to tackle light ... aye, just like the real thing.
Of course we can choose not to play, but when you have put effort into your team, trained them constantly, made sure you had a nicely balanced, well looked after squad, and the game just decides to hit you with injury after injury and silly losses against teams who are not being managed, where their manager never shows and the team look like they have never trained or changed ...
Yeah, you stick to that ideology.
There are so many fixes they could make with little effort and keep their customers happy, but nope, they refuse to do the sensible thing. Seems likt N are only interested in your money at times.