Indeed, Manchester United's performance has appeared to have improved quite rapidly in the last few matches so this victory is quite natural for them to get and also on the other hand, Aston Villa's performance is decreasing at the moment so Manchester United can take advantage of this to be able to win.
This is quite an important victory for Manchester United to continue to improve their position in the Premier League standings, even if Manchester United can continue to be consistent, I think it is not impossible that they can enter the top 4 positions.
They are improving but still far from top four with 6 points less than Tottenham Hotspur and 5 points less than Aston Villa. Those clubs are holding fourth and fifth positions on the table and Manchester United still have a long way to be able to get in top four.
Aston Villa are an underdog and surprisingly play well in this season but it's realistic to expect they will have significant drop in performance. It's what we are witnessing last one month and from a second position, they dropped to a fifth position. No longer are at a position that can challenge Liverpool or Manchester City, Arsenal for Premier League title.
Manchester United have their problems with biggest one is their unstable performance so that it's hard to believe they are stronger and better than Tottenham Hotspur and Aston Villa in rest of season. They can take this improvement as foundation for their race against those clubs and take over a fourth position.