United won the Manchester derby. It was really strange that City couldn't win this game despite having a full squad. Even though they focused on the game and had the ball throughout the match, they couldn't win. United managed to win the match with goals in the first half and won the cup.United performed poorly in the league but at least ended the season with a trophy
I'm glad that City got another slap in the face, it's especially nice in the derby. It seems to me that this defeat can be easily explained by the fact that the City players very much celebrated the victory in the Premier League (there are many photo evidence of this) and were out of shape because of this, plus there was an obvious underestimation of the opponent.
But I don't want to discount United's achievement and in the end the discipline problems are City's problems, they are to blame.