It's understandable tho, the drop of form of the GK and CDM as losing your main CBs does have a knock-on affect. Tho, as you rightly say, De Gea has those mistakes in him and it's doubtful that'll ever change.
Seen a lot criticise him due to his ball distribution, or lack of, comparing against the top teams GKs who play as a sweeper. Not sure if it's justified with De Gea tho.
Rashford. He's always been very hot and cold, plenty of promise but ... This year seemed to be different as he was consistently white hot perhaps what's happening now is a display of his true levels?
Ten Hag? I spoke about him previously and he has improved players. Well, he did until now. Is he a myth? Sure, you've had injuries but still shouldn't be dropping this many points.
Agree about the Cup win. Don't get me wrong, you've done better this year and deserve some credit but I do worry for you that the improvement hasn't been enough as Liverpool, Chelsea, Spurs won't be this bad again next year. And City plus Arsenal will only get better.
Liverpool? Yeah, I think we've been lucky tbh and I'm not getting carried away with our form. Which is why I'm confident you'll stay top 4 as our luck won't last the rest of the season as we've been pretty terrible in patches also.
Momentum is something tho, so maybe we just keep pushing on? Who knows as we're much improved ... which isn't hard