#2 Poor Defending
This performance might finally convince the United board to invest heavily on the United defense in the summer. United were extremely poor against Everton in the final third, but they lost the game due to their horrible defending.
It was very easy for the home team to find the gaps between the opposition defense, as Jones and Smalling failed to assert their influence in their own box and allowed the home team to dominate them.
The United back four had no support from their midfield either. Matic had a horrible return to the first team and allowed everyone to run past him. Fred tried his best to drop down and help his defense but he was poor too. There was a space between the United midfield and defense that was never closed down by the away side. Everton ran into this area and made full use of the time and space to punish United.
Manchester United failed to defend as a unit and looked vulnerable every time Everton came forward. Their woeful defending ultimately cost them the game.