Let's focus on EPL only.
We scored 64 goals in the league, 2nd best in the league, can't say we are poor in offence. The fact that we made so many elementary error in defence, only to be rescued by the attacking power. Agree that unreliability of Martial and James, and relying too much on Rashford and Bruno, is a problem, and they should share part of the responsibility of us being 2nd, but our topic of discussion is on CB.
As for defence, ignoring the 1st 2 loss, in fact I would ignore the Arsenal loss, so let's talk about
LC-MU, MU-EV, WBA-MU - Draw
MU-SH Loss
These are 9 points dropped, points that should not have dropped. Adding 9 points to our table, where will we be? OK we are still no. 2, but breathing down the neck of City.