I don't see where the overreactions are.
The reality is that most fans were excited to finally have a manager worth his salt in charge of a team that was massively improved over the summer finally be able to play these kinds of games and reflect the on-paper superiority onto the pitch, and win the match comfortably.
Instead we got more of the same from the last three years, a pathetic display where you just knew United would concede late after a disjointed performance where openings were rarely created, let alone exploited. Lo and behold, that's exactly what happened.
Save the bullshit excuses about "not being up for the Europa League". Get off your high horse, we're in this tournament for a reason. You play a competitive game against a team you're much better than, you expect to win; whatever the competition. The notion that the tournament has any impact on their will to win just reflects even worse on them and their mental state during these games.
Just stop making excuses. That was our second defeat in a row and it was an extremely disappointing display and result and those involved are being called out on it. There's nothing wrong with saying that.